Crime SceneCrime Scene

Officer in charge of investigation determines Officer in charge of investigation determines when crime scene may be safely returned to when crime scene may be safely returned to public accesspublic access

Protect the area from accidental or Protect the area from accidental or intentional contamination by anyone, intentional contamination by anyone, including police officers and other official including police officers and other official personnelpersonnel

s.129 of the Code, obstructing a police officer s.129 of the Code, obstructing a police officer in the lawful execution of his/her duties; in the lawful execution of his/her duties; gives police authority to cordon off and gives police authority to cordon off and refuse entry to a crime scenerefuse entry to a crime scene

Crime Scene InvestigationCrime Scene Investigation

Security of the scene falls under the Security of the scene falls under the coroner’s authority in the following coroner’s authority in the following cases:cases: Sudden or unexpected deathsSudden or unexpected deaths Deaths of person in custodyDeaths of person in custody Deaths occurring in institutions, agedDeaths occurring in institutions, aged Deaths from violenceDeaths from violence SuicidesSuicides Deaths occurring in a suspicious, Deaths occurring in a suspicious,

unusual, or unnatural mannerunusual, or unnatural manner

Crime Scene InvestigationCrime Scene Investigation

Police officers may seize anything Police officers may seize anything relevant to the investigation at the relevant to the investigation at the crime scene and to maintain the crime scene and to maintain the security of the scene until it is security of the scene until it is ordered released by the coroner ordered released by the coroner following the post mortem following the post mortem examinationexamination

Processing the Crime SceneProcessing the Crime Scene

Focus of police investigation is the Focus of police investigation is the collection of physical evidencecollection of physical evidence

CSI (“Crime Scene Investigation”) CSI (“Crime Scene Investigation”) carried out by a mobile crime labcarried out by a mobile crime lab

Police prepare a Police prepare a descriptiondescription of what of what they findthey find

Police Police photographphotograph a scene a scene Police prepare Police prepare diagramsdiagrams of sketches of sketches Police collect Police collect evidenceevidence

Crime Scene ProcedureCrime Scene Procedure

Important to safeguard the continuity Important to safeguard the continuity of evidence:of evidence: No exhibit is left unattended from the No exhibit is left unattended from the

time of its seizure until it is deposited in time of its seizure until it is deposited in the police property – stage facilitythe police property – stage facility

The officer who seized the item, or the The officer who seized the item, or the case officer, must secure the evidence case officer, must secure the evidence in the police property locker, which is in the police property locker, which is under the control of the property clerkunder the control of the property clerk

Crime Scene ProcedureCrime Scene Procedure

The transfer of any evidence to the The transfer of any evidence to the forensic laboratory is the responsibility of forensic laboratory is the responsibility of the case officer and/or his or her designatethe case officer and/or his or her designate

The transfer of evidence to and from court The transfer of evidence to and from court is the responsibility of the case officeris the responsibility of the case officer

No exhibit can be removed from the No exhibit can be removed from the control of the property clerk without the control of the property clerk without the appropriate authority and signatureappropriate authority and signature

The case officer is the officer in charge of The case officer is the officer in charge of the investigationthe investigation

Processing Physical EvidenceProcessing Physical Evidence

Forensic scientists job is to put the Forensic scientists job is to put the evidence together correctly like the evidence together correctly like the pieces of a puzzlepieces of a puzzle

Analysis of the evidence may involve Analysis of the evidence may involve biology, chemistry, physics, biology, chemistry, physics, anthropology, geology, and computer anthropology, geology, and computer sciencescience

Often called on to give expert Often called on to give expert testimony in courttestimony in court

FingerprintsFingerprints

Along with DNA, fingerprints are Along with DNA, fingerprints are considered by many to be the best considered by many to be the best way to identify a suspectway to identify a suspect

Fingerprints never change and are Fingerprints never change and are unique to each personunique to each person

Fingerprint patterns can be identified Fingerprint patterns can be identified as one of three types:as one of three types:

FingerprintsFingerprints

1. 1. ArchesArches, forming ridges that run , forming ridges that run from one side of the print to the from one side of the print to the other and curve up the middleother and curve up the middle

2. 2. LoopsLoops, showing stronger curves , showing stronger curves than arches with ends that start on than arches with ends that start on one side of the finger, loop around, one side of the finger, loop around, and end up in the same placeand end up in the same place

3. 3. WhorlsWhorls, forming complete ovals, , forming complete ovals, often in a spiral pattern around a often in a spiral pattern around a central pointcentral point

Latent FingerprintsLatent Fingerprints

Created when a person’s fingers Created when a person’s fingers come into contact with an object come into contact with an object such a piece of glass or of plasticsuch a piece of glass or of plastic

Created by a residue of oil and Created by a residue of oil and perspiration from the fingertipperspiration from the fingertip

Usually invisible and requires the Usually invisible and requires the application of chemicals or laser lightapplication of chemicals or laser light

Visible Impressions or FingerprintsVisible Impressions or Fingerprints

Result of a finger’s contact where Result of a finger’s contact where blood, dust or grease has been blood, dust or grease has been previously depositedpreviously deposited

FingerprintsFingerprints

Moulded fingerprints:Moulded fingerprints: Leaves a visible impression in a soft Leaves a visible impression in a soft

substance such as clay, wax or puttysubstance such as clay, wax or putty

Trace ElementsTrace Elements

Includes Includes dirtdirt, , dustdust, , fibresfibres and and residueresidue Origin of these materials may Origin of these materials may

provide a link between a suspect and provide a link between a suspect and a crimea crime

Material at an arson scene may Material at an arson scene may produce trace elements of an produce trace elements of an accelerant used to start or maintain accelerant used to start or maintain a firea fire

Trace ElementsTrace Elements

Further examination may uncover Further examination may uncover the specific chemical composition of the specific chemical composition of the fluid, thus linking it to a suspect the fluid, thus linking it to a suspect who possesses the same materialwho possesses the same material

Transfer of trace elements such as Transfer of trace elements such as hair and fibres between the hair and fibres between the perpetrator and the victim is perpetrator and the victim is common in crimes such as common in crimes such as homicides, aggravated assault and homicides, aggravated assault and kidnapping kidnapping

HairHair

If the sample contains the root, shaft If the sample contains the root, shaft and tip, it may reveal:and tip, it may reveal: a person’s racial backgrounda person’s racial background the area of the body from which the hair the area of the body from which the hair

originatedoriginated the person’s blood typethe person’s blood type

FibresFibres

Examination may determine their Examination may determine their point of origin or manufacturerpoint of origin or manufacturer

Matching the fibres found on the sole Matching the fibres found on the sole of the shoe of a victim with the of the shoe of a victim with the accuser’s residencesaccuser’s residences

BloodBlood

In impaired-driving offences, blood In impaired-driving offences, blood evidence is paramountevidence is paramount

Also relevant in cases where a Also relevant in cases where a suspect’s mens rea is in issue as a suspect’s mens rea is in issue as a result of intoxicating substancesresult of intoxicating substances

Blood is a fluid that conforms to the Blood is a fluid that conforms to the laws governing the motion and laws governing the motion and properties of other fluidsproperties of other fluids

BloodBlood

Study the size and shape of blood Study the size and shape of blood drops on a floor can indicate the drops on a floor can indicate the height from which they fell and thus height from which they fell and thus the location of the woundthe location of the wound

Shape may indicate movement; a Shape may indicate movement; a person in motion while bleeding person in motion while bleeding produces a tear-shape drop, with the produces a tear-shape drop, with the narrow end indicating the direction of narrow end indicating the direction of travel and the rounded end pointing travel and the rounded end pointing towards the bleedertowards the bleeder

BloodBlood

Blood splatter patterns on the wall Blood splatter patterns on the wall may indicate the force and direction may indicate the force and direction of a blow and indicate how far the of a blow and indicate how far the victim was from the wall when the victim was from the wall when the wound was inflictedwound was inflicted

Gunshot ResidueGunshot Residue Includes:Includes:

GasesGases Unburned or partially burned power grainsUnburned or partially burned power grains Carbon particlesCarbon particles Trace of the bullet lubricantTrace of the bullet lubricant Traces of primer components (lead, Traces of primer components (lead,

barium, nitrates)barium, nitrates) Fragments of soft bullets (lead antimony)Fragments of soft bullets (lead antimony) Fragments of the bullet jacketFragments of the bullet jacket Metal traces for the cartridge case or gun Metal traces for the cartridge case or gun

barrelbarrel

Gunshot ResidueGunshot Residue

These trace elements are deposited These trace elements are deposited on the hands of the person on the hands of the person discharging the gundischarging the gun

Under circumstances, detectable and Under circumstances, detectable and identifiableidentifiable

Gunshot Residue – Hand Wash Gunshot Residue – Hand Wash TestTest

Requires the suspect to wash his or Requires the suspect to wash his or her hands in a chemical solutionher hands in a chemical solution

Solution is then sent to the Solution is then sent to the laboratory for analysislaboratory for analysis

Test can detect elevated levels of Test can detect elevated levels of lead, barium, and antimonylead, barium, and antimony

May indicate that the suspect has May indicate that the suspect has fired a gun recentlyfired a gun recently

Gunshot ResidueGunshot Residue

GSR test cannot determine the time GSR test cannot determine the time at which the suspect may have fired at which the suspect may have fired the gunthe gun

It is less effective when the time It is less effective when the time between firing the fun and taking the between firing the fun and taking the hand wash exceeds four hourshand wash exceeds four hours

Gunshot Residue – Scanning Gunshot Residue – Scanning Electron Microscopy SEMElectron Microscopy SEM

Provides results that appear to be Provides results that appear to be more accurate and consistent than more accurate and consistent than the hand wash testthe hand wash test

Special utensil containing a gummed Special utensil containing a gummed substance is held against the skin substance is held against the skin and them removedand them removed

GSR adheres to the gummed GSR adheres to the gummed substance, which is then prepared substance, which is then prepared for examination by the scanning for examination by the scanning electron microscopeelectron microscope

DNA: Deoxyribonucleic AcidDNA: Deoxyribonucleic Acid

All human beings have a distinctive All human beings have a distinctive genetic code within their 46 genetic code within their 46 chromosomeschromosomes

Identification of an individual through Identification of an individual through his or her distinctive genetic codehis or her distinctive genetic code

DNA: Deoxyribonucleic AcidDNA: Deoxyribonucleic Acid

Minute samples of:Minute samples of: Blood including a blood stainBlood including a blood stain SemenSemen SalivaSaliva Vaginal secretionsVaginal secretions SkinSkin Hair folliclesHair follicles

Can be used…Can be used…

DNA: Deoxyribonucleic AcidDNA: Deoxyribonucleic Acid

Are sufficient to produce reliable results Are sufficient to produce reliable results even when the sample combines two or even when the sample combines two or more substancesmore substances

This contamination does not affect the This contamination does not affect the reliability of the testreliability of the test

Properly analyzed, it can identify an Properly analyzed, it can identify an individual with a certainty exceeding one individual with a certainty exceeding one in several billionin several billion

Has also been used to rule out suspects, or Has also been used to rule out suspects, or to overturn wrongful convictionsto overturn wrongful convictions