In Section 1 of this course you will cover these topics: Introduction The Crime Scene Physical Evidence Physical Properties: Glass And Soil

Transcription

1 1 Criminalists. In Sectin 1 f this curse yu will cver these tpics: Intrductin The Crime Scene Physical Evidence Physical Prperties: Glass And Sil Tpic : Intrductin Tpic Objective: After studying this tpic the student shuld be able t: Define and distinguish frensic science and criminalistics Recgnize the majr cntributrs t the develpment f frensic science Accunt fr the rapid grwth f frensic labratries in the past frty years Cmpare and cntrast the Frye and Daubert decisins relating t the admissibility f scientific evidence in the curtrm Explain the rle and respnsibilities f the expert witness

2 2 Definitin/Overview: Algr mrtis:pstmrtem changes that cause a bdy t lse heat. Autpsy:The medical dissectin and examinatin f a bdy in rder t determine the cause f death. Expert Witness: An individual whm the curt determines t pssess knwledge relevant t the trial that is nt expected f the average laypersn. Livr Mrtis: The medical cnditin that ccurs after death and results in the settling f bld in areas f the bdy clsest t the grund. Lcards Exchange Principle: Whenever tw bjects cme int cntact with ne anther, there is exchange f materials between them. Rigr Mrtis: The medical cnditin that ccurs after death and results in the stiffening f muscle mass. The rigidity f the bdy gradually disappears 24 hurs after death. Key Pints: 1. Criminalistics Criminalistics is the frensic science f analyzing and interpreting evidence using the natural sciences. Frensic science pertains t all sciences applied t legal prblems. CRIMINALISTS use the science f criminalistics t slve crimes. They examine and identify physical evidence t recnstruct a crime scene. Physical evidence can be a weapn, a piece f clthing, a bldstain, drugs, r even a vapr in the air. Criminalists use this physical evidence t prvide a link between a suspect and the victim. The transfer f clthing fibers r hair fibers between a suspect

3 3 and the victim can prvide just such a link. Fingerprints, bullets, and she impressins are ther imprtant links. Physical evidence is cllected frm a crime scene that includes the victim's bdy and the surrunding area f the crime. Criminalists cllect physical evidence at crime scenes and receive evidence at the labratry, which has been cllected at the crime scene by crime scene investigatrs. The prper cllectin f evidence is essential t prevent cntaminatin and destructin f the evidence. Once the evidence is brught t the crime lab, Criminalists cnduct tests depending n the type f evidence. Criminalists are ften called t curt t prvide expert testimny regarding their methds and findings. Serlgy is the analysis f bdy fluid evidence that includes bldstains, semen stains, and saliva. T determine the identity and rigin f the substance, Criminalists analyze bld dried int fabrics r ther bjects, as well as cigarette butts that may cntain saliva residues. Smetimes the stain is nt visible t the naked eye. Bld is usually visible due t its clr, but ften an artificial frensic light surce is necessary t see ther bdy fluid evidence. The stained evidence must remain dry and be stred at a cld temperature t maintain its integrity. DNA typing is pssible with a sample f bdy fluid such as bld, saliva, r semen. DNA typing prvides a Criminalist with a genetic blueprint that is unique t each persn. Criminalists then try t match the DNA typing results with a suspect. Prper handling and strage is essential t preserve DNA test samples. Trace evidence is the analysis f hairs, fibers, paint, glass, wd, and sil that are present at a crime scene. Examinatin f trace evidence helps t establish a relatinship between a suspect and the victim. A fiber may be taken frm the victim's bdy revealing the type f fiber frm carpet unique t the make and mdel f the suspect's car. Once trace evidence is discvered, a

4 4 Criminalist r ther investigatr cllects the evidence frm the crime scene by using a pair f jeweler's tweezers and immediately places the evidence in a flded paper cne and then int a sealed evidence envelpe. Trace evidence is later analyzed at the crime lab t determine its cmpsitin and rigin. Firearms and tlmarks analysis invlves the examinatin f any firearm that is suspected f being used in a criminal act. Criminalists can determine the kind f bullet used and whether it was fired frm the gun used t cmmit the crime. Tlmark analysis includes any bject suspected f cntaining the impressin f anther bject that served as a tl in the cmmissin f a crime. Fr instance, a screwdriver makes a distinctive impressin when scraped alng the surface f a wall. A Criminalist will analyze the marks the screwdriver left behind. Impressin evidence is the evaluatin f impressins made by shes, tires, depressins in sft sils, and all ther frms f tracks and impressins. Glve and ther fabric impressins, as well as bite marks in skin r fd, are included. Criminalists als btain impressins f dust frm surfaces t reveal fingerprints. Drug identificatin is used by Criminalists t analyze and identify illegal substances such as ccaine, herin, and marijuana, that are fund in plastic bags r vials at crime scenes. Criminalists must interpret the results f drug analyses in rder t determine their significance t the case. 2. Histry f Frensic Science The "Eureka" legend f Archimedes ( BC) can be cnsidered an early use f frensic anthrplgy. He determined that a crwn was nt cmpletely made up f gld (as it was fraudulently claimed). This cnclusin was reached by evaluating the density f the bject using measurements f its displacement and its weight, as he was nt allwed t damage the

5 5 crwn.the earliest accunt f fingerprint use t establish identity was during the 7th century. Accrding t an Arabic merchant, Sleiman, a debtr's fingerprints were affixed t a bill, which wuld then be given t the lender. This bill was legally recgnized as prf f the validity f the debt. The first written accunt f using medicine and entmlgy t slve (separate) criminal cases is attributed t the bk Xi Yuan Ji Lu (translated as "Cllected Cases f Injustice Rectified"), written in Sng Dynasty China by Sng Ci ( ) in In ne f the accunts, the case f a persn murdered with a sickle was slved by a death investigatr wh instructed everyne t bring his sickle t ne lcatin. Flies, attracted by the smell f bld, eventually gathered n a single sickle. In light f this, the murderer cnfessed. The bk als ffered advice n hw t distinguish between a drwning (water in the lungs) and strangulatin (brken neck cartilage), alng with ther evidence frm examining crpses n determining if a death was caused by murder, suicide, r an accident. In sixteenth century Eurpe, medical practitiners in army and university settings began t gather infrmatin n cause and manner f death. Ambrise Par, a French army surgen, systematically studied the effects f vilent death n internal rgans. Tw Italian surgens, Frtunat Fidelis and Pal Zacchia, laid the fundatin f mdern pathlgy by studying changes which ccurred in the structure f the bdy as the result f disease. In the late 1700s, writings n these tpics began t appear. These included: "A Treatise n Frensic Medicine and Public Health" by the French physician Fdr, and "The Cmplete System f Plice Medicine" by the German medical expert Jhann Peter Franck. In 1776, Swedish chemist Carl Wilhelm Scheele devised a way f detecting arsenus xide, simple arsenic, in crpses, althugh nly in large quantities. This investigatin was expanded, in 1806, by German chemist Valentin Rss, wh learned t detect the pisn in the walls f a victim's stmach, and by English chemist James Marsh, wh used chemical prcesses t cnfirm arsenic as the cause f death in an 1836 murder trial. Tw early examples f English frensic science in individual legal prceedings demnstrate the increasing use f lgic and prcedure in criminal investigatins. In 1784, in Lancaster, England, Jhn Tms was tried and cnvicted fr murdering Edward Culshaw with a pistl. When the dead bdy f Culshaw was examined, a pistl wad (crushed paper used t secure pwder and balls in

6 6 the muzzle) fund in his head wund matched perfectly with a trn newspaper fund in Tms' pcket. In Warwick, England, in 1816, a farm laburer was tried and cnvicted f the murder f a yung maidservant. She had been drwned in a shallw pl and bre the marks f vilent assault. The plice fund ftprints and an impressin frm crdury clth with a sewn patch in the damp earth near the pl. There were als scattered grains f wheat and chaff. The breeches f a farm laburer wh had been threshing wheat nearby were examined and crrespnded exactly t the impressin in the earth near the pl. Later in the 20th century, several British pathlgists, Bernard Spilsbury, Francis Camps, Sydney Smith and Keith Simpsn wuld pineer new frensic methds in Britain. 3. Frye and Daubert Prir t Daubert, relevancy in cmbinatin with the Frye test were the dminant standards fr determining the admissibility f scientific evidence in Federal curts. Frye is based n a 1923 Federal Curt f appeals ruling invlving the admissibility f plygraph evidence. Under Frye, the Curt based the admissibility f testimny regarding nvel scientific evidence n whether it has "gained general acceptance in the particular field in which it belngs." The trial curt's gatekeeper rle in this respect is typically described as cnservative, thus helping t keep pseudscience ut f the curtrm by deferring t thse in the field. In Daubert, the Supreme Curt ruled that the 1923 Frye test was superseded by the 1975 Federal Rules f Evidence, specifically Rule 702 gverning expert testimny. Rule 702 riginally stated (in its entirety), "If scientific, technical, r ther specialized knwledge will assist the trier f fact t understand the evidence r determine a fact in issue, a witness qualified as an expert by knwledge, skill, experience, training, r educatin, may testify theret in the frm f an pinin r therwise." In Daubert, the Curt ruled that nthing in the Federal Rules f Evidence gverning expert evidence "gives any indicatin that 'general acceptance' is a necessary precnditin t the admissibility f scientific evidence. Mrever, such a rigid standard wuld be at dds with the Rules' liberal thrust and their general apprach f relaxing the traditinal barriers t 'pinin'

7 7 testimny." Hwever, sme legal cmmentatrs argue that Daubert has resulted in a mre cnservative rather than liberal standard regarding the admissibility f expert evidence. The Daubert standard was refined by tw additinal Supreme Curt rulings; tgether knwn as the "Daubert trilgy." In General Electric C. v. Jiner, the Supreme Curt held that an abuse-fdiscretin standard f review was the prper standard fr appellate curts t use in reviewing a trial curt's decisin f whether expert testimny shuld be admitted. Thus, appellate curts must defer t the lwer trial curt's decisin regarding the admissibility f expert testimny unless they are strikingly wrng. In Kumh Tire C. v. Carmichael the Supreme Curt held that the judges gatekeeping functin identified in Daubert applies t all expert testimny, including that which is nn-scientific. In 2000, the Supreme Curt apprved amendments t the Federal Rules f Evidence relating t pinin evidence and expert testimny t cnfrm t the "Daubert trilgy." In additin t amending Rules 701 and 703, Rule 702 nw includes the additinal prvisins which state that a witness may nly testify if, "1) the testimny is based upn sufficient facts r data 2) the testimny is the prduct f reliable principles and methds, and 3) the witness has applied the principles and methds reliably t the facts f the case." The Daubert decisin was heralded by many bservers as ne f the mst imprtant Supreme Curt decisins f the last century imparting crucial legal refrms t reduce the vlume f what has disparagingly been labeled junk science in the curt rm. Many f these individuals were cnvinced by Peter Hubers 1991 bk Galiles Revenge: Junk Science in the Curtrm which argued that numerus prduct liability and txic trt verdicts were unjustly made n the basis f junk science. Accrding t Huber, junk science in the curts threatened nt nly justice but the wrkings f the American ecnmy. This threat rested n tw premises: Juries are nt cmpetent t recgnize flaws in scientific testimny, especially txic trt r prduct liability suits where decisins n causatin rested n cmplex scientific issues. The result f junk science is the issuance f jury awards that deter manufacturers frm intrducing wrthwhile prducts int the marketplace ut f fear f unwarranted trt liability fr injuries their prducts have nt caused.

8 8 By requiring experts t prvide relevant pinins grunded in reliable methdlgy, prpnents f Daubert were satisfied that these standards wuld result in a fair and ratinal reslutin f the scientific and technlgical issues which lie at the heart f prduct liability adjudicatin. Accrding t a 2002 RAND study, pst Daubert, the percentage f expert testimny by scientists that was excluded frm the curtrm significantly rse. This rise likely cntributed t a dubling in successful mtins fr summary judgment in which 90% were against plaintiffs. Beynd this study, there is little empirical evidence f the impact f Daubert. Hwever, sme critics argue that Daubert has disrupted the balance between plaintiffs and defendants, The exclusin f expert testimny affects plaintiffs far mre than defendants because plaintiffs may then nt be able t meet their required burden f prf. Furthermre, there is little pint in plaintiffs ging t the expense f Daubert mtins t exclude defendants experts until they knw if their case will prceed. S if mre experts are nw being excluded, then Daubert has undubtedly shifted the balance between plaintiffs and defendants and made it mre difficult fr plaintiffs t litigate successfully. Similarly, Daubert hearings can be subject t varius abuses by attrneys attempting t blster a weak case. These tactics can range frm simply attempting t delay the case t driving up the csts f the litigatin frcing settlement. A different pattern has emerged in criminal cases. In criminal cases, the prsecutin has the burden f prf and uses a hst f frensic science methds as evidence t prve their case. But, Daubert mtins are rarely made by criminal defendants and when they d, they lse a majrity f the challenges. Sme critics f the use f unreliable science in curt argue that Daubert has had beneficial effects in civil litigatin, but fails t address the underlying pathlgies f the frensic science system that leads t dubius verdicts in criminal cases. Sme cmmentatrs believe that Daubert caused judges t becmein the phrase used in frmer Chief Justice William Rehnquists dissent in Daubertamateur scientists, many lacking the scientific literacy t effectively fulfill their rle as gatekeeper f scientific evidence. Althugh science fr judges frums have emerged in the wake f Daubert in rder t educate judges in a variety f scientific fields, many are still skeptical abut the usefulness f the Daubert standard in discerning valid science. T summarize, five cardinal pints Daubert asks f every new technique in rder t be admissible in curt are:

9 9 Has the technique been tested in actual field cnditins (and nt just in a labratry)? [e.g. fingerprinting has been extensively tested and verified nt nly in labratry cnditins, but even in actual criminal cases. S it is admissible. Plygraphy n the ther hand has been well tested in labratries but nt s well tested in field cnditins] Has the technique been subject t peer review and publicatin? What is the knwn r ptential rate f errr? Is it zer, r lw enugh t be clse t zer? D standards exist fr the cntrl f the technique's peratin? [e.g. the use f penile plethysmgraphy fr sex ffender risk assessment is being used by different wrkers accrding t their wn standards. Thus penile plethysmgraphy des nt meet Daubert criteria] Has the technique been generally accepted within the relevant scientific cmmunity? [this test was earlier the nly relevant criterin under Frye] The Supreme Curt explicitly cautined that the Daubert list shuld nt be regarded by judges as a definitive checklist r test Yet in practice, many judges regularly judge the admissibility f scientific evidence using the "Daubert factrs" as a checklist. 4. Expert Witness Typically, experts are relied n fr pinins n severity f injury, degree f insanity, cause f failure in a machine r ther device, lss f earnings, care csts, and the like. In an intellectualprperty case, an expert may be shwn tw music scres, bk texts, r circuit bards and asked t ascertain their degree f similarity. The tribunal itself, r the judge, can in sme systems call upn experts t technically evaluate a certain fact r actin, in rder t prvide the curt with a cmplete knwledge n the fact/actin it is judging. The expertise has the legal value f an acquisitin f data. The results f these experts are then cmpared t thse by the experts f the parties. The expert has a heavy respnsibility, especially in penal trials, and perjury by an expert is a severely punished crime in mst cuntries. The use f expert witnesses is smetimes criticized in the United States because in civil trials, they are ften used by bth sides t advcate differing psitins, and it is left up t a jury f laymen t decide which expert witness t believe.

10 10 Smetimes ne side has utilized an expert witness t prvide fraudulent r junk science testimny in rder t cnvince a jury. Such experts are cmmnly disparaged as "hired guns." In England and Wales, under the Civil Prcedure Rules 1998 (CPR), an expert witness is required t be independent and address his r her reprt t the Curt. A witness may be jintly instructed by bth sides if the parties agree t this, especially in cases where the liability is relatively small. Under the CPR, expert witnesses are usually instructed t prduce a jint statement detailing pints f agreement and disagreement t assist the curt r tribunal. The meeting is held quite independently f instructing lawyers, and ften assists in reslutin f a case, especially if the experts review and mdify their pinins. When this happens, substantial trial csts can be saved when the parties t a dispute agree t a settlement. In mst systems, the trial (r the prcedure) can be suspended in rder t allw the experts t study the case and prduce their results. Mre frequently, meetings f experts ccur befre trial. Tpic : The Crime Scene Tpic Objective: After studying this tpic the student shuld be able t: Define physical evidence Discuss the respnsibilities f the first plice fficer wh arrives at a crime scene Explain the steps t be taken t thrughly recrd the crime scene Describe prper prcedures fr cnducting a systematic search f a crime scene fr physical evidence Describe prper techniques fr packaging cmmn types f physical evidence Define and understand the cncept f chain f custdy

11 11 Definitin/Overview: Buccal swab: A swab f the inner prtin f the cheek; cheek cells are usually cllected t determine the DNA prfile f an individual. Chain f custdy: A list f all peple wh came int pssessin f an item f evidence. Finished sketch: A precise rendering f the crime scene, usually drawn t scale. Physical evidence: Any bject that can establish that a crime has been cmmitted r can link a crime and its victim r its perpetratr. Rugh sketch: A draft representatin f all essential infrmatin and measurements at a crime scene. This sketch is drawn at the crime scene. Standard/reference sample: Physical evidence whse rigin is knwn, such as bld r hair frm a suspect, that can be cmpared t crime-scene evidence. Substrate cntrl: Uncntaminated surface material clse t an area where physical evidence has been depsited. This sample is t be used t ensure that the surface n which a sample has been depsited des nt interfere with labratry tests. Key Pints: 1. Physical evidence Physical evidence is any evidence intrduced in a trial in the frm f a physical bject, intended t prve a fact in issue based n its demnstrable physical characteristics. Physical evidence can cnceivably include all r part f any bject.

12 12 In a murder trial fr example (r a civil trial fr assault), the physical evidence might include DNA left by the attacker n the victim's bdy, the bdy itself, the weapn used, pieces f carpet spattered with bld, r casts f ftprints r tire prints fund at the scene f the crime. Where physical evidence is f a cmplexity that makes it difficult fr the average persn t understand its significance, an expert witness may be called t explain t the jury the prper interpretatin f the evidence at hand. A piece f evidence is nt physical evidence if it merely cnveys the infrmatin that wuld be cnveyed by the physical evidence, but in anther medium. Fr example, a diagram cmparing a defective part t ne that was prperly made is dcumentary evidencenly the actual part, r a replica f the actual part, wuld be physical evidence. Similarly, a film f a murder taking place wuld nt be physical evidence (unless it was intrduced t shw that the victims bld had splattered n the film), but dcumentary evidence (as with a written descriptin f the event frm an eyewitness). 2. First Plice Officer Mst plice investigatins begin at the scene f a crime. The scene is simply defined as the actual site r lcatin in which the incident tk place. It is imprtant that the first fficer n the crime scene prperly prtect the evidence. The entire investigatin hinges n that first persn being able t prperly identify, islate, and secure the scene. The scene shuld be secured by establishing a restricted perimeter. This is dne by using sme type f rpe r barrier. The purpse f securing the scene is t restrict access and prevent evidence destructin. It is the duty f the first plice fficer n the scene t take any steps necessary t make certain that the scene is kept as undisturbed as pssible. If there t much mvement at the scene by t many peple, vital evidence is likely t be mved r destryed.:securing a scene can be very

13 13 cmplicated say in the case f a fire r a rad accident as the preservatin f life will take precedence ver anything else. Once the scene is secured, the restrictins shuld include all nnessential persnnel. An investigatin may invlve a primary scene as well as several secndary scenes at ther lcatins. On majr scenes a safe space r cmfrt area shuld be designated at the crime scene t brief investigatrs, stre needed equipment, r as a break area. In critical incident management the prtcl that is being taught tday identifies a three layer r tier perimeter. The uter perimeter is established as a brder larger than the actual scene, t keep unlkers and nnessential persnal safe and away frm the scene, an inner perimeter allwing fr a cmmand pst and cmfrt area just utside f the scene, and the cre r scene itself. An extreme advantage will be seen by taking the time t prperly teach the unifrm fficers and first respnders t evaluate and secure the scene. 3. Recrding a Crime Scene Plice fficers and crime scene examiners will have limited time t investigate a scene, it is imprtant therefre t recrd the scene, nrmally thrugh still phtgraphy and videtaping by specialist phtgraphers. Sketch diagrams and cntempraneus ntes by attending plice fficers will als be imprtant in recrding the scene. 3.1 The Camera Frensic phtgraphers usually prefer t use 35 mm cameras, r medium frmat, as it tends t balance the prtability and ease f use with quality images. When taking clseup phts f evidence, the camera is ften munted nt a tripd fr stability t ensure the necessary quality required f phtgraphs presented as evidence in curt. Sme frensic labs have their wn darkrm facilities, which then enable phtgraphers t develp the pictures themselves.

14 Digital Cameras Digital cameras have a number f advantages when used in frensic phtgraphy as they require n chemical prcessing, can be displayed n the camera straight after being taken t ensure that the image was captured and the phts can be immediately transferred t a cmputer and stred in the database. Hwever, digital phts are very easy t alter which therefre prevents them frm being used as evidence in curt. 3.3 Vide Cameras Vide cameras als prvide an easy and inexpensive way t dcument crime scenes and can give the jury with a mre realistic sense f the crime scene than still pictures f a rm. The zm n vide cameras are hwever,mre ften digital rather than ptical and thus prvide pictures f slightly less clarity than actual phtgraphs. Vides are in general a gd briefing tl fr plice fficers wh have nt visited the crime scene. 3.4 Techniques Clse-up shts f evidence have precise requirements, such as exactness, angle taken and balance, in rder t achieve the best pssible shts. These pictures f evidence frm a factual recrd and must be able t be reprduced in terms f size, shape and clur, thus, balance and accuracy is an abslute must. The use f basic camera flash and fld lights are quite sufficient fr general crime scene phtgraphy, but clse-up shts f evidence require careful lighting. Artificial surces f light have prved very useful in the phtgraphy f evidence. An example f this cncerns blique-angled light, whereby the light is angled r slanted twards the subject. This is used fr bringing ut the detail in textured surfaces, such as ft and she prints left in mud. 3.5 Light With the help f clured filters and adaptable light-guides, lamps can direct a narrw beam f light at the subject f the phtgraph t enhance the bject details. Different light filters als allw fr the expsure f distinct evidence. Fr example, ultravilet light can make stains and fingerprints glw, vilet makes gunsht residue and bld mre visible and blue and green lights are used with enhanced fingerprints t shw up

15 15 fibres and urine. This is because sme materials absrb the ultravilet light, while thers reflect it, causing the material t becme present under the ultravilet light and flash f the camera when the pht is taken. A crime scene is als dcumented by writing dwn what the scene was like upn discvery, sketching, videing, evidence tables t dcument artifacts fund, vice recrding and witness interviews. 4. Systematic screening f the scene fr evidence Searching the crime scene is bviusly imprtant, hw it is carried ut depends n the scene. It may be as small and cntained as a single rm r it may be as large as a frest. It may include the dead (r living) bdy f the victim. Whatever the scene the search has t be as systematic and thrugh as pssible. Training is imprtant, but s als is experience as it is ften the experience eye which will pick up smething that des nt seem "quite right". The gal f the evidence-cllectin stage is t find, cllect and preserve all physical evidence that might serve t recreate the crime and identify the perpetratr in a manner that will stand up in curt. Evidence can cme in any frm. Sme typical kinds f evidence a CSI might find at a crime scene include: Trace evidence (gunsht residue, paint residue, brken glass, unknwn chemicals, drugs) Impressins (fingerprints, ftwear, tl marks) Bdy fluids (bld, semen, saliva, vmit) Hair and fibers Weapns and firearms evidence (knives, guns, bullet hles, cartridge casings) Questined dcuments (diaries, suicide nte, phne bks; als includes electrnic dcuments like answering machines and caller ID units)

16 16 With theries f the crime in mind, CSIs begin the systematic search fr incriminating evidence, taking meticulus ntes alng the way. If there is a dead bdy at the scene, the search prbably starts there. 4.1 Examining the bdy A CSI might cllect evidence frm the bdy at the crime scene r he might wait until the bdy arrives at the mrgue. In either case, the CSI des at least a visual examinatin f the bdy and surrunding area at the scene, taking pictures and detailed ntes. Befre mving the bdy, the CSI makes nte f details including: Are there any stains r marks n the clthing? Is the clthing bunched up in particular directin? If s, this culd indicate dragging. Are there any bruises, cuts r marks n bdy? Any defense wunds? Any injuries indicating, cnsistent with r incnsistent with the preliminary cause f death? Is there anything bviusly missing? Is there a tan mark where a watch r ring shuld be? If bld is present in large amunts, des the directin f flw fllw the laws f gravity? If nt, the bdy may have been mved. If n bld is present in the area surrunding the bdy, is this cnsistent with the preliminary cause f death? If nt, the bdy may have been mved. Are there any bdily fluids present beside bld? Is there any insect activity n the bdy? If s, the CSI may call in a frensic entmlgist t analyze the activity fr clues as t hw lng the persn has been dead. After mving the bdy, he perfrms the same examinatin f the ther side f the victim. At this pint, he may als take the bdy temperature and the ambient rm temperature t assist in determining an estimated time f death (althugh mst frensic scientists say that time f death determinatins are extremely unreliable -- the human bdy is unpredictable and there are t many variables invlved). He will als take fingerprints f the deceased either at the scene r at the ME's ffice.

17 17 Once the CSI is dne dcumenting the cnditins f bdy and the immediately surrunding area, technicians wrap the bdy in a white clth and put paper bags ver the hands and feet fr transprtatin t the mrgue fr an autpsy. These precautins are fr the purpse f preserving any trace evidence n the victim. A CSI will usually attend the autpsy and take additinal pictures r vide ftage and cllect additinal evidence, especially tissue samples frm majr rgans, fr analysis at the crime lab. 4.2 Examining the scene There are several search patterns available fr a CSI t chse frm t assure cmplete cverage and the mst efficient use f resurces. These patterns may include: Tpic : Physical Evidence Tpic Objective: After studying this tpic the student shuld be able t: Review the cmmn types f physical evidence encuntered at crime scenes Explain the difference between the identificatin and cmparisn f physical evidence Define and cntrast individual and class characteristics f physical evidence Appreciate the value f class evidence as it relates t a criminal investigatin Definitin/Overview: Class characteristics: Prperties f evidence that can be assciated nly with a grup and never with a single surce.

18 18 Cmparisn: The prcess f ascertaining whether tw r mre bjects have a cmmn rigin. Identificatin: The prcess f determining a substances physical r chemical identity. Drug analysis, species determinatin, and explsive residue analysis are typical examples f this undertaking in a frensic setting. Individual characteristics: Prperties f evidence that can be attributed t a cmmn surce with an extremely high degree f certainty. Prduct rule: Multiplying tgether the frequencies f independently ccurring genetic markers t btain an verall frequency f ccurrence fr a genetic prfile. Recnstructin: The methd used t supprt a likely sequence f events by bserving and evaluating physical evidence and statements made by thse invlved with the incident. Key Pints: 1. Physical Evidence Physical evidence is any bject that culd link a suspect t a crime scene, a victim t a crime scene, r it can tell us smething abut whether a crime has taken place r nt. Nw, what is an bject? That in itself is pretty interesting. An bject can be anything such as a gun r it can be a bullet, but it als can be smething as small as a human cell, because with current technlgy we can extract infrmatin frm a single cell that can tell us smething abut the DNA type f an individual that was present at the crime scene. S I use the term 'bject' very lsely. It can be anything frm the large t the infinitely small.

19 19 2. Types f Physical Evidence There are certain items that we see n a repeated basis at crime scenes, such as hairs, fibers, paint chips, glass, guns, bullets, cartridges, and different types f rpes. Als, what's interesting and very imprtant are these carriers f physical evidence - things that we see at scenes that smebdy may have tuched with their lips r their fingers and have depsited a finger print r DNA nt. We're nt ging t knw much abut that until we get it back t the crime lab and we have it analyzed. The types f physical evidence that can be cllected frm crime scenes vary greatly and depend heavily n lcatin and type f crime. Fr example, the physical evidence available fr cllectin at the scene f a rbbery is quite different frm that available at a murder scene. Physical evidence might include marks n a victim's bdy, such as abrasins r bite marks. Fingerprints n a dr r a windw frame als cnstitute physical evidence, as des bld left behind by a likely perpetratr. Trace evidence is a type f physical evidence that can be cllected and frensically examined; this kind f evidence is cmmnly depicted in CSI episdes. Trace evidence is fund when a small amunt f material has transferred frm either ne lcatin r persn t anther lcatin r persn. Examples f trace evidence include gunsht residue and fibers frm clthing r carpeting. 2. Trace evidence Trace evidence might include gun-sht residue (GSR), paint residue, chemicals, glass and illicit drugs. T cllect trace evidence, a CSI might use tweezers, plastic cntainers with lids, a filtered vacuum device and a knife. He will als have a bihazard kit n hand cntaining dispsable latex glves, bties, face mask and gwn and a bihazard waste bag. If the crime invlves a gun, the CSI will cllect clthing frm the victim and anyne wh may have been at the scene s the lab can test fr GSR. GSR n the victim can indicate a clse sht, and GSR n anyne else can indicate a suspect. The CSI places all clthing in sealed paper bags

20 20 fr transprt t the lab. If he finds any illicit drugs r unknwn pwders at the scene, he can cllect them using a knife and then seal each sample in a separate, sterile cntainer. The lab can identify the substance, determine its purity and see what else is in the sample in trace amunts. These tests might determine drug pssessin, drug tampering r whether the cmpsitin culd have killed r incapacitated a victim. Technicians discver a lt f the trace evidence fr a crime in the lab when they shake ut bedding, clthing, twels, cuch cushins and ther items fund at the scene. At the CBI Denver Crime Lab, technicians shake ut the items in a sterile rm, nt a large, white slab cvered with paper. The technicians then send any trace evidence they find t the apprpriate department. In the Denver Crime Lab, things like sil, glass and paint stay in the trace-evidence lab, illicit drugs and unknwn substances g t the chemistry lab, and hair ges t the DNA lab Bdy fluids Bdy fluids fund at a crime scene might include bld, semen, saliva, and vmit. T identify and cllect these pieces f evidence, a CSI might use smear slides, a scalpel, tweezers, scissrs, sterile clth squares, a UV light, prtective eyewear and luminl. He'll als use a bld cllectin kit t get samples frm any suspects r frm a living victim t use fr cmparisn. If the victim is dead and there is bld n the bdy, the CSI cllects a bld sample either by submitting a piece f clthing r by using a sterile clth square and a small amunt f distilled water t remve sme bld frm the bdy. Bld r saliva cllected frm the bdy may belng t smene else, and the lab will perfrm DNA analysis s the sample can be used later t cmpare t bld r saliva taken frm a suspect. The CSI will als scrape the victim's nails fr skin -- if there was a struggle, the suspect's skin (and therefre DNA) may be under the victim's nails. If there is dried bld n any furniture at the scene, the CSI will try t send the entire piece f furniture t the lab. A cuch is nt an uncmmn piece f evidence t cllect. If the bld is n smething that

21 21 can't reasnably g t the lab, like a wall r a bathtub, the CSI can cllect it by scraping it int a sterile cntainer using a scalpel. The CSI may als use luminl and a prtable UV light t reveal bld that has been washed ff a surface. If there is bld at the scene, there may als be bld spatter patterns. These patterns can reveal the type f weapn that was used -- fr instance, a "cast-ff pattern" is left when smething like a baseball bat cntacts a bld surce and then swings back. The drplets are large and ften tear-drp shaped. This type f pattern can indicate multiple blws frm a blunt bject, because the first blw typically des nt cntact any bld. A "highenergy pattern," n the ther hand, is made up f many tiny drplets and may indicate a gun sht. Bld spatter analysis can indicate which directin the bld came frm and hw many separate incidents created the pattern. Analyzing a bld pattern invlves studying the size and shape f the stain, the shape and size f the bld drplets and the cncentratin f the drplets within the pattern. The CSI takes pictures f the pattern and may call in a bld-spatter specialist t analyze it Hair and Fibers A CSI may use cmbs, tweezers, cntainers and a filtered vacuum device t cllect any hair r fibers at the scene. In a rape case with a live victim, the CSI accmpanies the victim t the hspital t btain any hairs r fibers fund n the victim's bdy during the medical examinatin. The CSI seals any hair r fiber evidence in separate cntainers fr transprt t the lab. A CSI might recver carpet fibers frm a suspect's shes. The lab can cmpare these fibers t carpet fibers frm the victim's hme. Analysts can use hair DNA t identify r eliminate suspects by cmparisn. The presence f hair n a tl r weapn can identify it as the weapn used in the crime. The crime lab can determine what type f animal the hair came frm (human? dg? cw?); and, if it's human, analysts can determine the persn's race, what part f the bdy the hair came frm, whether it fell ut r was pulled and whether it was dyed.

22 Fingerprints Tls fr recvering fingerprints include brushes, pwders, tape, chemicals, lift cards, a magnifying glass and Super Glue. A crime lab can use fingerprints t identify the victim r identify r rule ut a suspect. There are several types f prints a CSI might find at a crime scene: Visible: Left by the transfer f bld, paint r anther fluid r pwder nt a surface that is smth enugh t hld the print; evident t the naked eye Mlded: Left in a sft medium like sap, putty r candle wax, frming an impressin Latent: Left by the transfer f sweat and natural ils frm the fingers nt a surface that is smth enugh t hld the print; nt visible t the naked eye A perpetratr might leave prints n prus r nnprus surfaces. Paper, unfinished wd and cardbard are prus surfaces that will hld a print, and glass, plastic and metal are nn-prus surfaces. A CSI will typically lk fr latent prints n surfaces the perpetratr is likely t have tuched. Fr instance, if there are signs f frced entry n the frnt dr, the utside dr knb and dr surface are lgical places t lk fr prints. Breathing n a surface r shining a very strng light n it might make a latent print temprarily visible. When yu see a TV detective turn a drknb using a handkerchief, she's prbably destrying a latent print. The nly way nt t crrupt a latent print n a nn-prus surface is t nt tuch it. Prper methds fr recvering latent prints include: Pwder (fr nn-prus surfaces): Metallic silver pwder r velvet black pwder A CSI uses whichever pwder cntrasts mst with the clr f material hlding the print. He gently brushes pwder nt the surface in a circular mtin until a print is visible; then he starts brushing in the directin f the print ridges. He takes a pht f the print befre using tape t lift it (this makes it stand up better in curt). He adheres clear tape t the pwdered print, draws it back in a smth

23 23 mtin and then adheres is t a fingerprint card f a cntrasting clr t the pwder. Chemicals (fr prus surfaces): Idine, ninhydrin, silver nitrate The CSI sprays the chemical nt the surface f the material r dips the material int a chemical slutin t reveal the latent print. Cyanacrylate (Super Glue) fuming (fr prus r nn-prus surfaces) The CSI purs Super Glue int a metal plate and heats it t abut 120 F. He then places the plate, the heat surce and the bject cntaining the latent print in an airtight cntainer. The fumes frm the Super Glue make the latent print visible withut disturbing the material it's n Ftwear Impressins and Tl Marks A latent fingerprint is an example f a tw-dimensinal impressin. A ftwear impressin in mud r a tl mark n a windw frame is an example f a threedimensinal impressin. If it's nt pssible t submit the entire bject cntaining the impressin t the crime lab, a CSI makes a casting at the scene. A casting kit might include multiple casting cmpunds (dental gypsum, Silicne rubber), snw wax (fr making a cast in snw), a bwl, a spatula and cardbard bxes t hld the casts. If a CSI finds a ftwear impressin in mud, she'll phtgraph it and then make a cast. T prepare the casting material, she cmbines a casting material and water in a Ziplc-type bag and kneads it fr abut tw minutes, until the cnsistency is like pancake batter. She then purs the mixture int the edge f the track s that it flws int the impressin withut causing air bubbles. Once the material verflws the impressin, she lets it set fr at least 30 minutes and then carefully lifts the cast ut f the mud. Withut cleaning

24 24 the cast r brushing anything ff it (this wuld destry any trace evidence), she puts the cast int a cardbard bx r paper bag fr transprt t the lab. Fr tlmark impressins, a cast is much harder t use fr cmparisn than it is with ftwear. If it's nt feasible t transprt the entire item cntaining the tl mark, a CSI can make a silicne-rubber cast and hpe fr the best. There are tw types f tl marks a CSI might find at a crime scene: Impressed: A hard bject cntacts a sfter bject withut mving back and frth (fr example, a hammer mark n a dr frame). The tl mark is an impressin f the tl's shape. It's difficult t make a definite match with an impressed tl mark. Striated: A hard bject cntacts a sfter bject and mves back and frth (fr example, pry marks n a windw frame). The tl mark is a series f parallel lines. It's easier t make a definite match with a striated tl mark. In tlmark analysis, the lab might determine what srt f tl made the mark and whether a tl in evidence is the tl that made it. It can als cmpare the tl mark in evidence t anther tlmark t determine if the marks were made by the same tl Firearms If a CSI finds any firearms, bullets r casings at the scene, she puts glves n, picks up the gun by the barrel (nt the grip) and bags everything separately fr the lab. Frensic scientists can recver serial numbers and match bth bullets and casings nt nly t the weapn they were fired frm, but als t bullets and casings fund at ther crime scenes thrughut the state (mst ballistics databases are statewide). When there are bullet hles in the victim r in ther bjects at the scene, specialists can determine where and frm what height the bullet was fired frm, as well as the psitin f the victim when it was fired, using a laser trajectry kit. If there are bullets embedded in a wall r dr frame, the CSI cuts ut the prtin f the wall r frame cntaining the bullet -- digging the bullet ut can damage it and make it unsuitable fr cmparisn Dcuments A CSI cllects and preserves any diaries, planners, phne bks r suicide ntes fund at a crime scene. He als delivers t the lab any signed cntracts, receipts, a trn up letter in the trash r any ther written, typed r phtcpied evidence that might be

25 25 related t the crime. A dcuments lab can ften recnstruct a destryed dcument, even ne that has been burned, as well as determine if a dcument has been altered. Technicians analyze dcuments fr frgery, determine handwriting matches t the victim and suspects, and identify what type f machine was used t prduce the dcument. They can rule ut a printer r phtcpier fund at the scene r determine cmpatibility r incmpatibility with a machine fund in a suspect's pssessin. Whenever a CSI discvers a piece f evidence at the scene, she phtgraphs it, lgs it, recvers it and tags it. An evidence tag may include identificatin infrmatin such as time, date and exact lcatin f recvery and wh recvered the item, r it may simply reflect a serial number that crrespnds t an entry in the evidence lg that cntains this infrmatin. The crime scene reprt dcuments the cmplete bdy f evidence recvered frm the scene, including the pht lg, evidence recvery lg and a written reprt describing the crime scene investigatin Bite Marks Bite marks are fund many times in sexual assaults and can be matched back t the individual wh did the biting. They shuld be phtgraphed using an ABFO N. 2 Scale with nrmal lighting cnditins, side lighting, UV light, and alternate light surces. Clr slide and print film as well as black and white film shuld be used. The mre phtgraphs under a variety f cnditins, the better. Older bitemarks which are n lnger visible n the skin may smetimes be visualized and phtgraphed using UV light and alternate light surces. If the bitemark has left an impressin then maybe a cast can be made f it. Casts and phtgraphs f the suspect's teeth and maybe the victim's teeth will be needed fr cmparisn. Fr mre infrmatin cnsult a frensic dntlgist Fracture Matches Fracture matches can psitively link brken pieces at the scene with pieces fund in the pssessin f a suspect. Fr example, headlight fragments fund at the scene f a hit and run culd be psitively matched t a brken headlight (just like putting tgether a jigsaw puzzle) n a suspect's vehicle. Larger fragments shuld be placed in paper bags r envelpes. Smaller fragments shuld be placed in a paper packet and then placed in an envelpe.

26 26 While searching the scene, a CSI is lking fr details including: Are the drs and windws lcked r unlcked? Open r shut? Are there signs f frced entry, such as tl marks r brken lcks? Is the huse in gd rder? If nt, des it lk like there was a struggle r was the victim just messy? Is there mail lying arund? Has it been pened? Is the kitchen in gd rder? Is there any partially eaten fd? Is the table set? If s, fr hw many peple? Are there signs f a party, such as empty glasses r bttles r full ashtrays? If there are full ashtrays, what brands f cigarettes are present? Are there any lipstick r teeth marks n the butts? Is there anything that seems ut f place? A glass with lipstick marks in a man's apartment, r the tilet seat up in a wman's apartment? Is there a cuch blcking a drway? Is there trash in the trash cans? Is there anything ut f the rdinary in the trash? Is the trash in the right chrnlgical rder accrding t dates n mail and ther papers? If nt, smene might have been lking fr smething in the victim's trash. D the clcks shw the right time? Are the bathrm twels wet? Are the bathrm twels missing? Are there any signs f a cleanup? If the crime is a shting, hw many shts were fired? The CSI will try t lcate the gun, each bullet, each shell casing and each bullet hle. If the crime is a stabbing, is a knife bviusly missing frm victim's kitchen? If s, the crime may nt have been premeditated. Are there any she prints n tile, wd r linleum flrs r in the area immediately utside the building? Are there any tire marks in the driveway r in the area arund the building? Is there any bld splatter n flrs, walls r ceilings?

27 27 The actual cllectin f physical evidence is a slw prcess. Each time the CSI cllects an item, he must immediately preserve it, tag it and lg it fr the crime scene recrd. Different types f evidence may be cllected either at the scene r in lab depending n cnditins and resurces. Mr. Claytn, fr instance, never develps latent fingerprints at the scene. He always sends fingerprints t the lab fr develpment in a cntrlled envirnment. In the next sectin, we'll talk abut cllectin methds fr specific types f evidence. 5. Chain f custdy Chain f custdy refers t the chrnlgical dcumentatin, and/r paper trail, shwing the seizure, custdy, cntrl, transfer, analysis, and dispsitin f evidence, physical r electrnic. Because evidence can be used in curt t cnvict persns f crimes, it must be handled in a scrupulusly careful manner t avid later allegatins f tampering r miscnduct which can cmprmise the case f the prsecutin tward acquittal r t verturning a guilty verdict upn appeal. The idea behind recrding the chain f custdy is t establish that the alleged evidence is in fact related t the alleged crime - rather than, fr example, having been planted fraudulently t make smene appear guilty. Establishing chain f custdy is especially imprtant when the evidence cnsists f fungible gds. In practice, this mst ften applies t illegal drugs which have been seized by law enfrcement persnnel. In such cases, the defendant at times disclaims any knwledge f pssessin f the cntrlled substance in questin. Accrdingly, the chain f custdy dcumentatin and testimny is presented by the prsecutin t establish that the substance in evidence was in fact in the pssessin f the defendant. An identifiable persn must always have the physical custdy f a piece f evidence. In practice, this means that a plice fficer r detective will take charge f a piece f evidence, dcument its cllectin, and hand it ver t an evidence clerk fr strage in a secure place. These transactins, and every succeeding transactin between the cllectin f the evidence and its appearance in curt, shuld be cmpletely dcumented chrnlgically in rder t withstand legal challenges t the authenticity f the evidence. Dcumentatin shuld include the cnditins under which the

28 28 evidence is gathered, the identity f all evidence handlers, duratin f evidence custdy, security cnditins while handling r string the evidence, and the manner in which evidence is transferred t subsequent custdians each time such a transfer ccurs (alng with the signatures f persns invlved at each step). An example f "chain f custdy" wuld be the recvery f a bldy knife at a murder scene: Officer Andrew cllects the knife and places it int a cntainer, then gives it t frensics technician Bill. Frensics technician Bill takes the knife t the lab and cllects fingerprints and ther evidence frm the knife. Bill then gives the knife and all evidence gathered frm the knife t evidence clerk Charlene. Charlene then stres the evidence until it is needed, dcumenting everyne wh has accessed the riginal evidence (the knife, and riginal cpies f the lifted fingerprints). The chain f custdy requires that frm the mment the evidence is cllected, every transfer f evidence frm persn t persn be dcumented and that it be prvable that nbdy else culd have accessed that evidence. It is best t keep the number f transfers as lw as pssible. In the curtrm, if the defendant questins the chain f custdy f the evidence it can be prven that the knife in the evidence rm is the same knife fund at the crime scene. Hwever, if there are discrepancies and it cannt be prven wh had the knife at a particular pint in time, then the chain f custdy is brken and the defendant can ask t have the resulting evidence declared inadmissible. Chain f custdy is als used in mst chemical sampling situatins t maintain the integrity f the sample by prviding dcumentatin f the cntrl, transfer, and analysis f samples. Chain f custdy is especially imprtant in envirnmental wrk where sampling can identify the existence f cntaminatin and can be used t identify the respnsible party.