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Criminology Page
Ident Page

Ident Notes (You will still have to read the book) If he didn't go so damn fast on the overheads.

Identification of the criminal act


Fingerprints and photographs


- Police powers to take fingerprints depend on the nature of the charges preferred. In Canada, there are three types of offence with which a person can be charged: (1) indictable, (2) dual-procedure (hybrid), and (3) summary conviction


Use of force


(2) Such force may be used as in necessary to the effectual carrying out and application of the measurements, processes and operations described under subsection (1)




Criminal investigations are seldom successfully concluded without the assistance of specialized sections of Police Department and outside agencies which applies to Agent Investigation


Definition of Arson: The act of willfully and in some cases fraudulently setting fire to a building or other structures


Authority of a Peace Officer


Classification of fires


Fire can be classified in three (3) categories:


  1. Natural – i.e. sun, lightening, spontaneous combustion
  2. Accidental – children playing with matches, electrical, smoking
  3. Non-accidental – Arson


Assistance in determining cause:


Who can assist the investigation in determining the cause of a fire?

-         Fire Commissioner’s Office

-         Insurance Crime Prevention Bureau


Definition of fire: Fire is that which is produced when a substance undergoes rapid oxidation involving heat and light


Three things that are required or must be present to havr a fire


  1. Fuel – i.e. paper, cloth, wood
  2. Oxygen – Approximately 16% oxygen in atmosphere will cause extensive damage
  3. Heat – Ignition source i.e. match, candle, chemical, etc.


Flash Point – The lowest temperature to which a substance must be heated in order for the substance to give off volatile vapors which will burn when exposed to a flame or ignition source




-         During the course of a fire, the investigator should keep in mind the color of the flame and smoke

This information could be very essential in determining if the fire was of accidental nature or non-accidental nature


Color of smoke – Determine what type material was burning


Color of flames – Indicates at what temperature the fire was burning


Another mean of determining what temperatures the fire was burning at, is to examine the scene for different metals and the degree in which it melted







  1. Scene Protection
  2. Interview witnesses
  3. Scene Examination – outside
  4. Scene Examination – inside
  5. Analyze area of origin
  6. Consider total circumstances
  7. Request investigation
  8. Maintain continuity of the scene
  9. Seizure of exhibits – perishable


(1) Scene Protection

-         Guard

-         Rope off area

-         Barricade

-         Lock up


(2) Interview Witnesses

-         Color of smoke

-         Color of flame

-         Explosion

-         Size of fire when first noticed

-         Odors

-         Exterior openings –normal – locked – blocked


(3) Scene Examination Outside

- Damages to trees, shrubs, fence, outbuilding (direction of wind)

- Be suspicious of holes burnt through exterior walls at low levels

- Holes burnt through exterior walls (good indication of point of origin)

- Doors and windows for forceful entry

- Look for containers

- Dark smoky stains – visible on exterior walls windows and doors. Always heaviest ar doors or windows of room in which fire begins



Normal Fire – glass outside


(4) Examination of scene (inside)


To locate point of origin you proceed from the area of least to the deepest (one inch – 45 minutes)


Lowest level of charring should indicate point of origin


Examine ceilings – heaviest burning and exposed rafters can indicate point of origin


Pointers – plastic hangers – light bulbs


Looking for a V pattern – wide V – slow burning – narrow V – fast burning


(5) Analyze Area Of origin


At this point, you are to determine if the fire was an accident or non-accidental in nature


Accidental Nature – Heating System – Electrical appliances – Smoking


Non-Accident – Be suspicious or inverted “V” patterns. This is a sign that an accelerant heavier that the density of air was utilized


-         Look for made ventilation

-         Odors – Gas – Kerosene

-         Furnishing – Removal objects valuables

-         Clothing – check debris for buttons, zippers, etc

-         Locked windows, blocked doors

-         Bottom of doors – charred

-         Two or more points of origin

-         Floors charred – unusual

-         Trailers – candles,


(6) Consider Circumstances


(7) Request for Assistance


(8) Maintain continuity of the scene


Seize Exhibits – Perishable


No Plastic Bags


Freeze exhibit if it can not be submitted to Crime Detection Laboratory immediately


3 main parts to a camera


  1. The lens
  2. The body
  3. The back of the camera



Aperture ring – controls the volume of light entering the camera

Focusing ring – is some other important parts of the camera



Shutter – another important part of the camera is that it controls the amount of time you want the light to be exposed. The less light you have, you slower the shutter should be


ISO – How sensitive the film is to light


2 main reasons for un-sharp photographs – Focus and steadiness or the picture


Overview, range, 


Behavioral Objectives:


  1. Definition of physical evidence
  2. Examples of physical evidence
  3. Who is responsible for the collection of physical evidence
  4. Who is responsible for the examination of physical evidence
  5. How to protect the scene prior to the examination for physical evidence
  6. How to search the scene for physical evidence


Q. What is physical evidence?

A. Things that tend to prove or disprove something


Q. What is the value of physical evidence to investigation?

A. Proves or disproves a point



Examination of Physical evidence


Q. Who examines the physical evidence?

A. Field identification technician crime detection laboratories


Q. Who collects the physical evidence?

A. The investigator


Protect the scene


Q. How is the scene protected?

A. – Barriers

     - Guards

     - Lock doors

     - Don’t touch

     - Cover perishable items


Q. How would search be conducted?


-         Survey the scene – How?

-         No physical actions

-         Notes

-         Assistance – complainant

-         Look with a purpose




Q. Who examines scene for physical evidence?

A. Field ident technicians/Crime detection laboratories



Teaching Points


Testimonial, Documentary and Physical


What is the difference between Direct and Circumstantial evidence?


Evidence which leads to appoint at issue without needing inferences or deductions is said to be “direct”. Evidence which requires drawing conclusions is called “indirect” or “circumstantial”



Before evidence can be considered by the triers of fact, the judge must decide that it is admissible. Although admissibility is governed by rules, the judge has the final word


What determines the admissibility of evidence?

Relevant – relates to the facts at issue


Material – substantial importance to affect a point at issue

Competent – source qualified to present the evidence




All evidence carries weight which is gauged by the triers of fact. Finding one hit of evidence can often give you leads to finding more.


Corpus Delicti – elements that establish the foundation of the crime. Showing that an offence and therefore had an opportunity to commit it.


Searching Sequence


Protect the scene


Plan where to search and the order in which you will tackle the indicated areas. Consider the possibility of finding evidence along the offender’s escape route, at his home, in his place of business or on his person.


Try to form some ideas of what you can expect to find.


- Look for anything unusual or out of place.

- Be thorough and take your time.

- Have another officer conduct a second search.


Collecting Sequence:


When in doubt collect it.

- Mark all items that are not too small or fragile with at least your initial, date and time

- Have another officer witness the collection and mark the item.

- Package each item so that it will not be damaged, contaminated, or destroyed.

- Seal each container. If the item cannot be marked, mark the container.


Record the collection in your field notes and have the witness record it in their notes as well.


Once the finding and the collecting of an item have been recorded and witnessed, it is absolutely vital to keep a complete record of the chain of custody with signed receipts to show each time the item changes hands.


Discuss your evidence in detail with the prosecutor. Consider both the strong and weak points of your case.


Review all your material a few days before trial to refresh your recollection. Make sure everything is ready and that your expert witnesses will be available.




Exhibits associated with any crime scene can vary in type, physical structure, perishability and susceptibility to change. Standards vary on how each item should be submitted to the forensic laboratory


The term EXHIBIT describes an item having evidential value and its source may be unknown


The term CONTROL sample describes an item of known source which is to be used for comparison with the exhibit


Photographs and Sketches


Before collecting and exhibits, photographs the scene including details pertinent to the case


Take scaled photographs when practical, e.g. ruler placed beside the object or imprint for scale purposes


If you are unable to take photographs of the scene, prepare a sketch, preferably to scale


Selection of Exhibits


The investigator is responsible for deciding what exhibits should be submitted to the laboratory


Identify only physical evidence which can be potentially significant


Contact with biological materials such as blood, urine, semen, intact human organs, and corpses cane pose serious health hazard and occur through;


-         Poor blood sampling techniques

-         Open cuts and wounds and

-         Breathing aerosols emitted by biological material


The following are precautions to be taken


-         Wear thin, disposable, clean latex or nitrile gloves at all times when handling biological material, e.g. accidents, autopsies

-         Avoid inhaling air close to biological material which may contain contaminated aerosols

-         Thoroughly clean and disinfect equipment which has been in contact with biological material

-         Common disinfectants include rubbing alcohol and liquid bleach


Unless specifically instructed otherwise, do not add preservatives to exhibits


Allow exhibits to air-dry at room temperature. Do not use fans as the may blow away trace evidence. Do not accelerate dying by using heaters


EXCEPTION – if the exhibit is to be examined for the presence of foreign hair or fibers, use plastic bags. The use of clear plastic bags may eliminate the need to open bags containing biologically hazardous material in court


-         There should be no chemical interaction between container and contents

-         The size of the container should allow for processes of expansion

-         The size of the container should be compatible to the exhibit

-         All containers must be clean

-         In most cases, exhibits should be individually packaged

-         Transparent containers are more  convenient and reduce the handling of the


-         You can purchase most containers and packaging materials at local retail outlets

-         Containers such as vacuum tubes (with or without preservations) plastic vials, metal tins etc., may be purchased at most scientific and laboratory supply outlets


Marking Exhibits


Mark exhibits in a manner which permits identification to prove continuity of possession


-         If identifying are placed directly on exhibits, position them so as not to interfere with forensic laboratory examinations or to unnecessarily detract from their value or appearance

-         Do not identify exhibits by means of file headings or notations which may be construed as being prejudicial to the case


-         Seal each container. If the item cannot be marked, mark the container


Physical evidence: Things that have been approved or disapproved a theory i.e. knife, gun, etc.

Testimonial evidence: Get on the stand

Documentary evidence: threat letter, anything that is a document


Direct evidence

Circumstantial evidence



-         Overabundance of sweat glands on the hands and feet

-         Core and delta must be visible to be sent to Ottawa  

-         Roll from the point of resistance to the point of least resistance

-         Roll from thumb to small finger

-         Core is in the center and delta is below the core and to the sides

-         Know the name (identification of criminal act) and know what it is. (use of force)

-         Types of evidence

-         Idents responsibility to examine the scene

-         Fist thing to do when you get to the scene, protect the scene, guard, barriers, DON’T TOUCH ANYTHING

-         Definition of physical evidence

-         Relevant, material to the case, person giving evidence must be competent

-         Definition of continuity

-         Know how to mark exhibits

-         Definition corpus delecti (date, time, and initial)

-         Direct and circumstantial evidence

-         What to collect at a crime scene

-         Mark the items, the bag not the item itself

-         Know the arson aspect that was explained in this site

-         3 types of fires and examples

-         Know flash points

-         Motives for arson  (competition, cover up a crime, pyro, insurance

-         Definition of arson (willfully)

-         Point of origin

-         Color of smoke and what you can determine from it

-         Definition of perishable

-         Collecting sequence at an arson scene

-         Look for your exhibits at the point of origin

-         Read the photography section on this site


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Here are the notes for corrections and policing