7 steps of preserving and recording the crime scene

5. maintain the chain of custody

- AKA "continuity of possession", the chain of custody must be established whenever evidence is presented in court as exhibit - this means that EVERY person who handles or examined the evidence must be accounted for - failure to maintain the chain of custody may lead to SERIOUS questions regarding the authenticity & integrity of the evidence and examination of it - evidence should be MARKED and TAGGED for identification, with the collector's INITIALS and the DATE of collection written directly on it - in fact, everyone who possesses the evidence MUST maintain a written record of its acquisition and disposition - to avoid confusion and to retain completed control of the evidence, the chain of custody should be kept at a MINIMUM

finished sketch

- PRECISE rendering of the crime scene - DRAWN to scale - must reflect the SAME info as in rough sketch - usually done w computer-aided drafting (CAD) software

sketches

- a rough sketch, when necessary, contains an accurate depiction of all the dimensions of the scene and shows the location of ALL objects having a bearing on the case - whereas, a finished sketch is a precise rendering of the crime scene, usually DRAWN TO SCALE

packaging DNA evidence

- can be packaged in the same containers as biological evidence - package evidence and seal the package - package each item separately - biohazard label - NO plastic bags (due to mold)

what can cause changes to occur to evidence ?

- contamination - breakage - evaporation - accidental scratching or bending - improper or careless packaging

rough sketch

- drawn AT the scene (usually freehand w pencil) - NOT drawn to scale - a compass showing NORTH - shows the location of ALL items having a bearing on the case - distances MUST be accurate - a legend or list is used

4. collecting physical evidence

- each clothing item should be handles CAREFULLY and wrapped SEPARATELY - critical areas of the crime scene should be VACUUMED - fingernails SCRAPED w dull object - deceased victims must be autopsied to establish the CAUSE and MANNER of death

2. record the scene what are the 3 methods of this ?

- photography, sketches & notes are the three methods for crime scene recording - if objects are removed, positions change, or items added, the photographs may NOT be admissible as evidence at a trial, and their intended value will be lost

items used for packaging evidence

- unbreakable plastic pill bottles (hairs, glass, fibers and various other kinds of small or trace evidence) - manilla envelopes, glass vials, sealable plastic bags or metal pillboxes (most trace evidence) - airtight containers such as paint cans or jars (charred debris from fire) - paper folded in a "druggist fold" (powder, fine particles)

packaging biological evidence (blood, saliva, semen)

- use ONLY disposable tools to collect - blood should ONLY be packaged in wrapping paper, manila envelopes or paper bags (after being air-dried) ; mold can form in airtight packaging - place a RED biohazard label on the packaging

how to prevent changes to evidence

- using latex gloves - non-disposable equipment should be cleaned and/or sanitized between collecting each piece of evidence - do NOT move evidence until its location and appearance have been documented in notes, sketches & photographs - keep evidence in its original condition found at the site - do NOT remove blood, hair, fibers, soil particles, etc

7. submit evidence to the lab

- usually submitted to the lab by PERSONAL delivery or by MAIL shipment (determined by distance and urgency of the case) - packaged CAREFULLY in order to prevent breakage or other accidental destruction in transit - MUST have an evidence submission form - MUST state the specific test(s) needed for the evidence

photography and photographic procedures

-area in which the crime took place AND all adjacent areas -overview photographs of the ENTIRE scene, including entry and exit points -body position and location (IF the scene includes a body) -close up photos depicting injuries and weapons near the body -the surface beneath the body, once it's been removed from the crime scene -relative position and location of PHYSICAL evidence -a RULER or other measuring tool may be used to show scale size

7 steps of preserving and recording the crime scene

1. secure and isolate the crime scene 2. record the scene 3. search for evidence 4. collect and package evidence 5. maintain the chain of custody 6. obtain standard / reference samples 7. submit evidence to the lab

3. search for evidence

a crime-scene search will depend on : - the locale - size of the area - actions of the suspect(s) and victims(s) at the scene

buccal (buckle) swab

a swab of the inner portion of the cheek, used to collect cells for DNA profiling

grid method

basically a double-line search; effective but time-consuming

line or strip method

best in large, outdoor scenes

wheel or ray method

best on small, circular crime scenes

why are unauthorized personnel excluded ?

every individual who enters the scene has the potential to destroy physical evidence even if by unintentional carelessness

who is unauthorized personnel ?

higher-level police officials, members of the press, emotionally charged neighbors, curiosity seekers

handling evidence

investigators must handle and process physical evidence in a way that PREVENTS any change from taking place between the time the evidence is removed from the crime scene and the time it is received by the crime lab

spiral method

may move inward or outward; best used where there are no physical barriers

zone / quadrant method

most effective in houses or buildings; teams are assigned small zones for searching

notes

must include : - DETAILED written description of the scene - LOCATION of any physical item(s) removed - TIME item(s) are discovered, and by WHOM - HOW and by WHOM evidence item(s) is packaged & marked ! :tape-recording notes can be taped much faster than they can be written, however, at some point the tape MUST be transcribed into written document

standard / reference sample

physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime scene evidence

6. obtain standard / reference samples

standard / reference sample, buccal (buckle) swab, substrate control

1. secure and isolate the crime scene

the FIRST officer arriving on the scene must preserve and protect the area as much as possible ! : 1st priority is to RENDER AID and arrest perpetuator

substrate control

uncontaminated surface material close to an area where physical evidence has been deposited; used to ensure that the surface on which a sample has been deposited doesn't interfere w lab tests