The Crime Scene

Vocabulary

Make a vocabulary page in your notebook for each of the following terms:•Primary Crime Scene•Secondary Crime Scene•Physical Evidence•CAD•Chain of Custody

Objectives

Identify the different roles and personnel involved in investigating a crime scene

Understand and explain the steps in processing a crime scene

Understand the process of collecting, storing, and transporting evidence

POLICE OFFICERS are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime.

The CSI UNIT documents the crime scene in detail and collects any physical evidence.

The DISTRICT ATTORNEY is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge.

The MEDICAL EXAMINER (if a homicide) may or may not be present to determine a preliminary cause of death.

SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis.

DETECTIVES interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence.

Crime Scene Personnel

INTERACTIVE

• Which of the crime scene personnel interests you the most? Why?

• Which would be your least favorite? Why?

Crime Scene Processing

Interview• Crime Scenes are secured by the first responding

police• Forensic scientist must interview the securing

officer(s) upon arrival• What happened? What crime took place?• How was it committed?• Remember not all of this information may turn out

to be true.

Examine the Scene• Examine the scene for ‘first impressions’…does it

correlate to the story you got from the first responders?

• Examine the scene for additional areas that need to be secured, possible evidence, points of entry/exit

Photograph the Scene

• Overall, wide shots• Close-ups of evidence (with

ruler)• Lots Of pictures…

Sketch the Scene

• Once photographs have been taken the CSI needs to sketch the scene

• First sketch=rough sketch• Later, a more polished or final sketch will be

drawn• Usually a ‘birds-eye’ view

Interactive!

• Create a rough sketch of the crime scene picture that follows…

Rough Sketch• The first drawing created upon arriving on scene• Doesn’t have to be ‘pretty’• Does need:– Accurate dimensions– Show location of all objects – Shows all evidence and evidence markers– Key or legend– Compass

Finished Sketch

• Constructed with care and concern for appearance

• Used in the courtroom• CAD

Notes

• Note taking must be a constant activity throughout the processing of a crime scene

• Detailed written description of the scene• Location and description of the evidence• Where the evidence was discovered, by whom,

who collected it, where it was sent• Notes of smells, feelings, things a camera cannot

capture• Audio recordings of notes can be used

Interactive!

• Take notes for the following crime scene…

Process the Scene

• Processing the scene is systematic documentation and search of a crime scene

• Begin a systematic search for evidence that may have been missed or is not obvious

• Search methods:– Spiral– Grid– Line – Quadrant

Collecting Physical Evidence

• After crime scene is thoroughly documented evidence collection begins

• Items should be handled carefully (gloves and tweezers) and bagged separately to avoid contamination

• Critical areas can be vacuumed and the sweepings saved for trace analysis

• Everything needs to be well labeled

Tools for Evidence Collection

• Forceps and Tweezers: picking up small objects

• Plastic bottles with lids: hairs, glass, fibers, trace evidence

• Manila envelopes/ Paper Bags: trace evidence• Bloodstained material should NOT be sealed

in plastic container (mold)• Burned debris MUST be stored in airtight

container

Chain of Custody

• Chain of Custody: List of all people who had possession of an item of evidence

• Usually recorded on bag/envelope/tube

What Evidence Would you Collect?

INTERACTIVE

• Using your notes as a guide, develop a checklist that you could bring to a crime scene to make sure you don’t forget anything

• Checklist should begin with your arrival on the scene

• You will be using your checklist to investigate 2 crime scenes in the next couple of weeks.