Crime Scene Investigation

Elkins

The Seven S’s of Crime Scene Investigation

1. Secure the scene

2. Separate the witnesses

3. Scan the scene

4. Seeing the scene

5. Sketch the scene

6. Search for evidence

7. Secure the collected evidence

6. Searching for Evidence

Depends on number of investigators

Walk the scene marking location of evidence, photo, sketch

Single investigator: use grid, linear or spiral

Group: linear, zone or quadrant pattern

Stick to one pattern and one supervisor

Patterns are systematic to ensure no area is left unsearched

Additional light for hair / fibers

Vacuum cleaner

Flashlight and forceps reduce picking up extraneous

Better to collect everything and not need it than fail to collect something and need it late

Grid

Linear

Quadrant/Zone

Spiral

7. Securing and Collecting Evidence

All evidence needs to be properly packaged, sealed, and labeled.

Specific procedures and techniques for evidence collection and storage must be followed.

An evidence log and a chain of custody document must be attached to the evidence container.

The Golden Hour – the window of opportunity to collect time-sensitive information or evidence

The evidence log should contain all pertinent information, including:

Case number, item inventory number, description of the evidence, name of suspect, name of victim, date and time of recovery, signature of person recovering the evidence, signature of any witnesses present during collection.

Packaging Evidence

Liquids and arson remains = airtight, unbreakable container

Biological evidence: breathable containers to reduce

Each item must be placed in a separate container, and sealed and labeled

The most fragile evidence is collected and packaged first

Druggist fold:

Crease a clean paper and place evidence in the X position

Fold in the left and right sides, and then fold in the top and bottom

Put the bindle into a plastic or paper evidence bag affixing a seal over the

opening

Write your name on the seal

Evidence Bag

Maintaining a chain of custody log is essential to present credible evidence in court

Chain of Custody

1. -Bag the evidence -Add identification -Seal it -Sign it across the sealed edge

2. -Sign over to a lab technician -Open bag on non-sealed edge

3. -Return items to the evidence bag -Seal evidence bag in another bag -Sign the evidence log

Forensic Science: Fundamentals

& Investigations, Chapter 2

What determines the type and manner of

collecting and preserving physical evidence?

The nature of the evidence

Q. What type of evidence is to be retrieved

from a deceased victim for examination in

the crime laboratory?

Clothing

Fingernail scrapings

Head and pubic hairs

“Orifice” swabs

Bullets

Hand swabs for gunshot residues

Analyze the Evidence

Facts result from collected evidence processed by the

forensic lab

Lead detectives aim to see how facts fit into the crime

scenario

Lab results can:

Show reliability of witness accounts

Establish the identity of suspects or victims

Show suspects to be innocent or link them with a scene

or victim

Forensic Files

https://www.youtube.com/wat

ch?v=-r4irK1k0Fc

https://www.youtube.com/wat

ch?v=mxvyZHX1bQ4

How was the crime scene protected?

What types of forensic evidence

were discovered at the scene?

What types of evidence were

discovered in the property of the

suspect?

What methods of science were used

to tie the evidence to the crime

scene?

What evidence was used to convict

the suspect?