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 EvidenceDepends 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.

Chain of Custody1. -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 logForensic 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

Reconstructing a Crime Scene

Crime scene reconstruction involves:

Forming a hypothesis of the sequence of events

From before the crime was committed through its commission

But wait…things just aren’t adding up between the evidence and the witnesses/suspect. Could this be staged?!

Staged Crime Scenes

When lab results don’t match up with the testimony of witnesses

Common examples:

Staging a fire—to cover bankruptcy Staging a suicide—to cover a murder Staging a burglary—to collect insurance money

Things to consider when determining staging occurred

Initially treat all death investigations as homicide

Do the type(s) of wounds found on the victim match the weapon employed?

Could the wounds be easily self inflicted?

Establish a profile of the victim through interviews with friends and family

Evaluate the behavior ( mood and actions) of the victim before the event

Evaluate the behavior ( mood and actions) of any suspects before the event

Corroborate statements with evidential facts

Reconstruct the eventConduct all forensic

examinations to determine the facts of the case