Rules of Criminal Procedure Investigation of the Crime Scene

Expectations CL2.01 explain processes of police investigation CL2.02 explain pre-trial procedures, including processing evidence

The Crime Scene Police have the right to cordon off the crime scene to make sure no evidence is lost or tampered with. Police can refuse entry to a crime scene. HOWEVER, if the incident involves a death, the coroner has jurisdiction over the area.

The Crime Scene Continued The area will be photographed and searched for items such as hair or fibre samples, blood, forced entry, physical struggle, fingerprints, footprints, or weapons ▫This is called forensic evidence. Police will also question witnesses about their knowledge of the crime or the persons involved.

Processing Physical Evidence: Fingerprints Forensic scientists analyze the information collected. Fingerprints are compared with those on file at the RCMP central repository in Ottawa. The patterns of ridges on our finger pads are unique: no two individuals—even identical twins—have fingerprints that are exactly alike.  Like a snowflake!

Injuries such as burns or scrapes will not change the ridge structure: when new skin grows in, the same pattern will come back. Dactyloscopy ▫ the practice of using fingerprints to identify someone.

Mistakes can be made in fingerprint identification ▫usually only a portion of a print is available and can be distorted and hard to read, especially in a messy crime scene situation (i.e., BLOOD!) It is extremely important that specialists are able to properly dust and lift fingerprints at a crime scene to be able to classify and match them to those in the database.

Classifying Fingerprints All fingerprints can be identified as one of three types: Arches, Loops, Whorls 1.Arches: forming ridges that run from one side of the print to the other and curve up the middle

2.Loops: showing stronger curves than arches with ends that start on one side of the finger, loop around and end up in the same place ▫Don’t get these confused with full circles or ovals.

3.Whorls: forming complete ovals, often in a spiral pattern around a central point.

Dusting for Fingerprints It is extremely important that specialists are able to properly dust and lift fingerprints at a crime scene to be able to classify and match them to those in the database. Dusting is a method that is used to lift prints from hard surfaces Chemicals are needed to lift prints off smooth surfaces

Fingerprints There are 2 types of prints: 1.Visible fingerprint: can be observed by the naked eye i.e. coated in blood or grease 2.Latent fingerprint: formed by natural oils and perspiration on the fingertip. Not visible to the naked eye.

Three methods are used to develop latent prints: 1.Graphite powder: used on non- absorbent surfaces i.e. metal plastic 2.Iodine fuming: used on surfaces such as paper and cloth 3.Laser beam: provides a transparent 3D structural picture by sending light though the print left on a surface by a finger and reproducing it on a digital camera

Handling Evidence There are strict procedures on the seizure, handling, and storage of evidence: 1.no evidence is left unattended; 2.the case officer must secure evidence in the police property locker; 3.transferring evidence is the responsibility of the case officer; 4.no evidence can be removed from property locker without appropriate authority and signature. This is to maintain the chain of custody of the evidence.

Trace Elements, Blood, DNA

Trace Elements Dirt, dust, residue Provides link between suspect and the crime Example: wood or other materials at an arson scene may produce trace elements of the accelerant used to start a fire. ▫During an investigation into a series of fires in Hamilton, experts linked the fluid used to start fires to fluid found in the garage of one of the suspects. Both samples were mixed in exactly the same proportions and were not sold by any other manufacturer.

The transfer of hair and fibres ▫Typically analyzed in homicides, kidnapping and aggravated assault Hair and fibers are trace elements because they can be found either on the victim or the accused. Hair may not reveal specific people (like fingerprints), but they can reveal racial background, area of the body the hair came from and the persons blood type.

Animal fur is more scaly than human hair Hair samples with the root can provide the most information – DNA us usually present.

Various Fibre Samples Fibers from the crime scene can be traced to criminals (Example: Carpet fibres from the crime scene found on the suspects shoe)

Blood Blood samples are important in impaired driving cases or crimes committed when under the influence ▫Percentage of alcohol or substance levels can be important in cases where mens rea is an issue.

Blood Spatter Analysis ▫study of the size and shapes of the drops on the floor can determine from the height at which they fell ▫Shape of drop can indicate movement ▫Blood spatter on the wall can determine force and direction of the blow. ▫Blood Spatter News ReportBlood Spatter News Report

DNA All human beings have a distinctive genetic code within their chromosomes which are composed of DNA ▫Deoxyribonucleic acid (DNA) Lab analysis of blood stains, semen, saliva, vaginal secretion, skin and hair follicles can lead to the identification of an individual through his or her distinctive genetic code.

Season 10, Episode 5 “Bloodsport”