LESSON PLAN Preventing Scene Contamination Through a PSA

LESSON PLAN Preventing Scene Contamination through a PSA

ACTIVITY Rethinking Our Murder and Kidnapping Scenes (45 minutes)

Applying Locard's Exchange Principle

Teacher leads the glass through an analysis of the first scene, the murder scene.

Teacher "According to Locard, the suspect should have left traces of himself at the scene and taken traces of the scene with him when he left.

The murder scene was a gravel and dirt parking lot. The body was found in the victim's car, in the parking lot. The simplest scenario would be that the suspect entered the parking lot and the car and strangled the victim in the car."

Questions 1 through 4 are answered by the class working as a group. Answers should be written by one of the students up on the white board. The teacher leads the discussion.

Question #1: How would the suspect leave traces of himself in the parking lot?"

Allow the students to hazard some guesses such as:

1. "If he walked in, he might have left footprints. Depending on where he stepped, the footprints might be clear enough to identify.
2. The distance between the footprints might allow an estimate to be made of how tall the suspect is.
3. He may have dropped something as he walked across the lot."

1. "If he drove in, his vehicle might have left tire tracks. Depending on how much gravel is present, what size the individual rocks are and whether or not there are clean patches of dirt, there may be identifiable tread patterns observed in the tracks.

1. Perhaps by observing where the suspect vehicle's track cross the victim's vehicle tracks, it might be possible to determine which subject arrived first.

1. The width of the tire tracks would give the investigator a rough idea of the size of the tires.

1. The distance between the tracks left by the wheels on the right side and the wheels on the left side, would give the investigator an idea of the size of the vehicle; a first step to describing the vehicle."

Question #2: What evidence would have been transferred from the parking lot to the suspect?

Allow the students to hazard some guesses such as:

1. "Gravel may be stuck in the sole of the suspect's shoe."
2. "Dirt and /or mud may be stuck to the sole of the suspect's shoe."
3. "Dust may have been kicked up as the suspect walked across the lot. The dust would be on the suspect's lower pant's leg."

Question #3: When the police drove into the lot, do you think that some of the evidence might have been disturbed? How?

1. The police could have run over the victim vehicle’s tire tracks.
2. The police could have run over the suspect vehicle’s tire tracks.
3. The police could have run over footprints left by the victim, the suspect or any witnesses.
4. Any trace evidence that fell from the suspect such as hair and fibers could have been run over.

Now, consider this quote from lesson #1,

Mrs. Dooley promptly went to the golf course. She drove into the lot at a high rate of speed and slammed on the brakes skidding across the gravel. As the officers looked up they saw Mrs. Dooley, a female white approximately 30 years of age, dark brown shoulder length hair, red blouse, tan pants run to the Ford while still talking on her cell phone. She yanked open the door and grabbed her husband.

Question #4: What would these actions, coupled with with the police actions examined in question #3, do to the evidence that was described in question 1 and 2?

1. Probably destroyed.

STUDENTS: Answer questions 5, 6 and 7 as individuals, in writing.

Begin by imagining the movements of the suspect as he, or she, entered the victim's car. What did he, or she touch? Where did they sit? What tool was used? Now answer questions 5, 6 and 7.

Question #5: What would the suspect have left behind, at the scene, as he entered the car, sat in the car, and murdered the victim in the car? Include where the evidence would be found?

1. Footprints in the dirt and gravel outside of the car door.
2. Fingerprints on the outside door handle.
3. Fingerprints on the inside door handle.
4. Fingerprints on the edge of the door and/or window.
5. Dust from the parking lot on the floorboards of the backseat, provided he got into the car while it was in the parking lot. If he entered at some other point, there may be dirt, gravel, leaves or other material that he tracked in.
6. If he leaned over the backseat to choke the victim, the suspect could have left hair and or fibers on the seatback and headrest.
7. Hair and fibers in the backseat.
8. DNA could have been transferred from the suspect to the top of the seatback and headrest.
9. DNA transferred from the perspiration of the suspect, to the victim as they struggled.
10. Fingerprints on the door when he removed the magnetic sign.

RUBRIK question #5:

FailStudent made no attempt to answer the questions, merely gave up.

DStudent made list of one to three items of evidence and did not describe where the evidence would be found.

CStudent made a list of 3 to 8 items of evidence and did not describe where it would be found.

BStudent listed 3 to 8 items of evidence and did describe where it would be found.

AStudent listed 9 + items of evidence and clearly described where it would be found.

Question #6: What would the suspect have taken with him when he left the car?

1. Fibers from the seat and headrest.
2. Hair from the victim.
3. DNA from the victim’s perspiration transferred during the struggle.
4. The pizza boxes.
5. The magnetic sign
6. Fibers from the floor’s carpet.

RUBRIK question #6:

FailStudent made no attempt to answer the questions, merely gave up.

DStudent made list of one or two items of evidence and did not describe where the evidence would be found.

CStudent made a list of 3 to 4 items of evidence and did not describe where it would be found.

BStudent listed 4 items of evidence and did describe where it would be found.

AStudent listed 4+ items of evidence and clearly described where it would be found.

Now, consider this quote from lesson #1,

As the officers leaped from their squad car, Mrs. Dooley dragged her husband out of his car and onto the gravel. She shook him. There was no response. She began yelling, "Wake up!"

Officer Jones leaned over, touched her shoulders and asked her to leave him be and move back. The answer was a scream, "Call an ambulance!" She clutched her husband to her chest refusing to let go.

Question #7: What would Mrs. Dooley's actions do to the evidence this time?

Teacher: The student's answers do not have to cover every possible item of evidence and its probable fate. It merely has to demonstrate that they are visualizing what the suspect's actions would have caused him to touch, what evidence might result, and what the evidence' final fate might have been. I would grade as follows:

FNo attempt to imagine the actions, the evidence that might result, and what would have happened to the evidence.

DSome attempt to imagine the suspect's actions but no logical extrapolation of the likely evidence results.

CSome of the suspect's likely actions described and a few items of evidence that likely resulted described in general terms.

BThe suspects likely actions were described with some degree of specificity, the likely items of evidence were listed.

AThe suspect's actions were described. The evidence was described and an explanation as to how the suspect's actions produced the evidence is included. The fate of the evidence at the hands of Mrs. Dooley is clearly described.