AJ 104

Crime Scene Evidence, Experiments, and Models

Freeze!!!

Introduction Real Evidence

Anything that can be perceived with the five senses, except, trial testimony.

Real Evidence Must be marked and formally

introduced into evidence The attorney who wishes to introduce

them must lay a foundation to establish the admissibility of the items in question.

Real Evidence Includes: Physical items

Guns, Knives Documents

Will be covered in the next chapter Exhibits

Models, renderings to depict a crime scene

Pictures Still, video, x-rays

Introduce Evidence In 4 Easy Steps (S.A.F.F.)

1. Show evidence to defense to examine (if desired)

2. Assign a number (the court clerk mark the evidence as People’s No. #)

3. Foundation is laid to establish the item is admissible.

4. Formal request is made to admit it into.

pg. 125

Crime Scene Evidence Items admitted must be authenticated

To show that an item is genuine To show is the same one described by

the witness The item needs to be the same condition

as it was found by the police unless tested

Careful handling of evidence and accurate report writing are crucial

WHY?

At the Crime Scene

Protect the evidence Restrict public access Do not clean the area Always better to have too many than

not enough Save everything of evidentiary value WHY?

Laying the Foundation

The series of questions an attorney asks witnesses in order to establish that a piece of evidence is admissible Have someone identify the object and

testify about where the item was found What has been done since it was taken

into the custody? WHY?

Marking & Packing, & Sketching Once an object is identified and can be

used as evidence, it should be marked at the time it is collected Before collecting and packaging , make a

detailed recordation of the crime scene/collection

Mark with the officer’s initial’s They should not be placed where they may

interfere with lab results Exercise caution preserve fingerprints,

blood, DNA, etc.

Marking & Packing, & Sketching

When possible, try to do as many f the following as possible:

Make sketches of the location (to scale) indicating where the object was found Locations of doors, windows,

Take photos of the area Make detailed notes

Real or Hollywood?

Real or Hollywood?

Real or Hollywood?

Crime Scene Sketch

Crime Scene Sketch

The proper packaging of evidence is extremely important Evidence needs to be preserved for trial Care must be taken not to damage,

evaporate or contaminate Each piece of evidence must be packaged

individually & labeled on the outside. Leave enough space for everyone who

handles the evidence will indicate the date, time, and reason for handling it.

Chain of Custody Also called “continuity of possession” It is necessary to account for

everyone who has had possession of the evidence in order to show the judge and jury that the evidence has not been tampered with.

Pg. 129 (sketch)

Scientific Evidence

Forensics Can be used to established the

elements of the crime Conclusively associate the defendant

with the crime, Help reconstruct the crime

Types of Cases Using Scientific Evidence Police are likely to clear a case when

scientific evidence is used. Jurors give scientific evidence serious

consideration, but is not the key element

2/3 of their cases involve: Drugs Narcotics Drunk Driving

Types of Cases Using Scientific Evidence

The next most common categories were: Firearms Blood & Bloodstains Semen

Forensic evidence was used in nearly all murder and drug possession cases.

Scientific Evidence, Laying the Foundation The foundation for the introduction of

scientific investigation involves answering three questions: Is this a valid scientific test? Was accurate equipment used for the test? Was this test performed in an appropriate

manner by a qualified person? Both sides will call their expert witnesses

to challenge the validity of the test.

Commonly Accepted Scientific Tests

Many tests are so well established that they are admitted at trial without a challenge to their validity. Identification of Controlled Substances Identification of Firearms Blood Alcohol Blood Typing DNA Testing

Tests Not Commonly Accepted Scientific tests must be accepted in

their field before the courts are willing to allow their use at trial Polygraph

The high frequency of inconclusive results makes the courts distrust the results of a polygraph

Hypnosis It is still a concern of the court being in a

trancelike state and being unconsciously responsive.

Experiments

Screens out all extraneous variables so that the experimenter ca measure the impact of one factor. Few experiments are introduced in

court