Evidence from a Crime Scene

• Physical evidence breaks into the following

• Transient

• Transfer

• Conditional

• Pattern

• Associated

Locard’s Theory

• Locard's exchange principle states that "with contact between two items, there will be an exchange" (Thornton, 1997).

• Essentially Locard's principle is applied to crime scenes in which the perpetrator(s) of a crime comes into contact with the scene, so the perpetrator(s) will both bring something into the scene and leave with something from the scene. Every contact leaves a trace.

Physical Evidence

• Transient – Certain aspects of a crime scene may manifest themselves only for brief periods. For instance, the distinctive smoke and odor an incendiary device emits may be evident only within the first few minutes. An exterior scene can be promptly compromised by weather.

Physical Evidence

• Transfer evidence is defined as any evidential substance or particle such as blood, fluids, hairs, fibers, paint, and skin that is exchanged between an assailant and the victim or the scene of the crime. Such evidence can transfer either from the criminal to the victim or from the victim to the criminal. It can also be transferred into or out of the crime scene. This transfer often occurs when forcible contact occurs between persons, vehicles, or objects.

Physical Evidence

• Conditional evidence is produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances or sequence within a particular event

• Examples may include lighting conditions at time, colour of flame and speed in which spread at a fire scene. In relation to animal investigations you would have to look at the state of the animal. Wounds, dehydrations, open sores, heat, cold and where found all have an impact on reconstruction of the crime.

Physical Evidence

• Pattern Pattern evidence is defined as any forensic evidence that can be read and analyzed from a specific type of pattern left by the physical contact between different people (such as victim and assailant), persons and objects (such as victim and automobile).

• Forensic experts examine all forms of pattern evidence in order to eliminate any possible accidental and natural causes for the pattern. For example, fires from flammable liquids often leave behind certain residue patterns.

• Animals can show a pattern of abuse if examined by a veterinarian. Such things as old wounds, fractures and the like tell a story

Physical Evidence • Associated Evidence is evidence that links two

separate entities, whether they are people, or objects. In other words, associative evidence relates to the evidence that links a person (or object) to the scene of the crime.

• latent fingerprints left on an object,

• fibers left from contact of clothing with objects,

• blood from physical injury,

• semen from sexual assault,

• saliva from spitting, cigarettes, or envelopes,

• hair shed at a scene,

• paint transferred during a burglary or automobile accident,

• glass transferred during a burglary or from a bottle used as a weapon,

• soil from a scene,

• impressions from tools, footwear, or tire.

Identification. Preservation and

Collecting Evidence • Physical Evidence primarily fits into two

categories

• Immovable

• Movable

Immovable Evidence

• Can be such things a damage to a building, marks on wall, plants, shrubbery, tool and weapon impressions

• Evidence can be both moveable and immovable (Skid marks from tires are immovable but residue from the tire can be removed, likewise paint chips on a permanent door frame)

Immovable Evidence

• Immovable evidence may be recorded in situ• The court always wants the best evidence possible

or that the circumstances will permit. On occasions it is possible to take the primary evidence or actual object to court (Best Evidence Rule)

• In other circumstances secondary evidence such as photos, video or sketches will have to be permitted

Methods of recording evidence

• Written descriptions

• Sketch plans

• Photographs

• Videotape

• Castings

• Lifting of imprints and fingerprints

Written Descriptions

• Should be in a proper note book

• Should include the date, time, conditions, and exact location where the evidence was located

• It should contain a complete and comprehensive description of the evidence and the circumstances under which the evidence was found

Written Descriptions

• Written descriptions should list the appearance, nature, size and physical attributes

• If able to be seized it should be marked with an identifying mark, tagged and securely stored

• If not able to be seized and immovable photograph and videotape

Sketch Plans

• Sketch plans are excellent for referral when testifying. They also allow us to gather our thoughts when at the scene.

• Sketches show the scene, record where objects were, where evidence was located and are effective when describing events and situations to others.

Photographs

• Although still photos provide an excellent means of recording, they can be taken in such a way as to distort. (Size and Impressions)

• Such distortions are very seldom deliberate but can have the same devastating effect at trial

Photographs

• Lawyers are aware that opposing counsel often photograph items or evidence from the best possible angle and position to better their case

• Place a ruler or some other object for comparison in size.

• Photograph from different angles and distances

Video Recording

• Is very effective • Always use a new tape for every case or incident.

Do not tape over. • Time and date started, time and date paused,

circumstances and reasons for stopping and pausing, and time date completed should be noted.

• Also put in all the circumstances surrounding the video, reasons rationale etc.

Control Samples

• It is often necessary to compare evidence with an item of known origin

• This item or sample of known origin is called a control sample.

• Dirt from a particular area• Substances which have a particular make up such

as a type of herbicide or poison.• Feces and blood samples from animals

Continuity

• Once evidence has been seized, photographed or videotaped it is up to the investigator to ensure the safekeeping of the evidence until it is needed.

• Continuity is best defined as an unbroken chain of possession which can account for evidence from the time it was seized or obtained until it was presented as evidence.

Continuity

• If kept personally, enter it in your notes, initial and keep in an area where no other person has access

• If given to another person make sure it is initialed, described in your notes and note the date, time and location it was given to the other person

• Have the person sign for it.

Continuity

• If continuity is an issue the opposing counsel will suggest that the evidence has been tampered with or that the evidence presented is not the evidence seized or the evidence has been altered in some way.

• The best way to win a case is by attacking the credibility and integrity of the evidence presented.

Preserving

• Physical evidence should never be touched by bare hands

• Use latex gloves

• Special care not to smudge any evidence such as fingerprints

• Do not transfer particles from one piece of evidence to another

Packaging

• Packaging should not alter the evidence

• Dry items can be placed in a new plastic bag although paper is preferred

• Larger items may be boxed and wrapped

• Damp items should be allowed to dry and then stored in a paper bag

• Liquid items should be placed in clean and appropriate bottles or vials.

Preserving

• The bag, box, vial or other form of packaging should be

• Sealed

• Signed with the date and time

• Attached should be a written description of the contents with a reference to the case, where, when and circumstances under which it was found

Liquids

• In a sterilized jar or recognized vial

• Sealed and noted as previously described

• Small amounts of liquid can be mopped up with a sterile, lint free gauze with is then placed in a sterile jar.

Large Amounts of Evidence

• Large amounts of evidence such a debris are often present

• Take a control sample

• May also take control samples from different locations

• Should photograph, videotape or make sketch where each sample was found and record in your notes.

Unique Evidence

• In most cases each piece of evidence is different in some way

• The objects uniqueness is usually defined by the fashion in which it was used or misused by its owner or handler

• Pens produced in mass quantities are not unique but as soon as a person owns it, it takes on characteristics of the owner, the same with shoes

Perishable Evidence

• Perishable items such as meat, vegetables, gases and liquids will alter their appearance and structure with the passage of time

• Gases and liquids stored in an air tight container • Food stuffs may be frozen in some instances • Other times you may only photograph• Items such as bananas, various fruits, and

vegetables do not freeze well.

6 Steps of Evidence Collection

• Collect – Self Explanatory

• Secure – As few people as possible have access to the evidence

• Preserve – The integrity of the evidence

• Identify – Who found the evidence and all the circumstances surrounding the finding of the evidence. (who what where when how and why) (Relevance)

• Continuity – A paper trail of who seized, initialed, how stored and when removed and returned for any reason.

• Log – Keeping the log is essential to continuity

Overall goal of investigator

To Maintain

• Legal integrity

• Scientific integrity

• Physical integrity

• Of all the evidence that is collected