crime scene investigation

INTRODUCTION TO BIOTECHNOLOGY

Group 2 Alyzsa Aqu ino Al ic ia Maria LayoLianne Balanay Charmaine Lover iaJack i lyn Bel loKaren EnclonaKeith Hi lamon

WHAT IS A CRIME SCENE?

The place where an offense has been committed and forensic evidence may be gathered.

A car riddled with bullets is pictured from October 10, 1942

Scene shots of a man who committed suicide on September 4, 1950

A detective points to a victim camouflaged in brush at a crime scene dated September 28, 1942

Crime Scene Investigation

How It’s Done

Samples That May be Collected at a Crime Scene

• biological evidence• latent print evidence• footwear and tire track evidence• trace evidence• digital evidence• tool and tool mark evidence• drug evidence• firearm evidence

The type of evidence

collected will vary with the type of crime.

• Photograph and document the scene

• Collect trace materials (especially from probable points of entry)

• Collect low-level DNA evidence by swabbing areas of likely contact

• Collect other items that may contain biological evidence

• Locate and collect latent fingerprints

A case will be investigated by a DETECTIVE who is responsible for interviewing persons of interest and victims, pursuing leads and piecing together the information that is developed from the materials collected at the scene.

Investigators can achieve four levels of certification through the International Association for Identification (IAI) that demonstrate their proficiency:

Certified Crime Scene Investigator

Certified

Crime

Scene Anal

yst

Certified

Crime

Scene

Reconstruc

tionist

Certified

Senior

Crime Scen

e Analyst

How a Crime Scene Investigation

is Conducted

1. Establish the scene dimensions and identify potential safety and health hazards.

2. Establish security3. Plan, communicate and coordinate4. Conduct a primary survey/walkthrough 5. Document and process the scene 6. Conduct a secondary survey/review7. Record and preserve evidence

How and Where Tests on the Evidence are Conducted

The most probative evidence will be sent to

either a forensic laboratory

To help identify the evidence that is most

valuable, the crime scene personnel may

conduct initial screening tests, called

presumptive tests, at the scene.

DNA Evidence:

Basics of Analyzing

1) the isolation of the DNA

from an evidence sample

containing DNA of unknown

origin, and generally at a

later time, the isolation of

DNA from a sample (e.g.,

blood) from a known

individual;

2) the processing of the DNA so that test results may be obtained;

3) the determination of the DNA test results (or types), from specific regions of the DNA;

4) the comparison and interpretation of the test results from the unknown and known samples to determine whether the known individual is not the source of the DNA or is included as a possible source of the DNA.

Steps in DNA

Sample Processing:

Biology

Tech

nology

Genetics

Ty

pe

s DN

A

Ev

ide

nce

An

aly

sis

Polymerase Chain Reaction (PCR)

Short Tandem Repeats (STR)

Y-Chromosome

Mitochondrial DNA

enables rese

archers to

produce mill

ions of copi

es

of a specifi

c DNA sequen

ce

in approxima

tely two

hours. This

automated

process bypa

sses the nee

d

to use bacte

ria for

amplifying D

NA.

Polymerase Chain Reaction

Short Tandem Repeats (STR)

STRs are usually considered “junk DNA” because they are introns and do not code for protein.

Mitochondrial DNA

contains

37 gene

s, all o

f which

are esse

ntial fo

r

normal m

itochond

rial fun

ction. T

hirteen

of these

genes pr

ovide in

structio

ns for m

aking en

zymes

involved

in oxid

ative ph

osphoryl

ation. T

he

remainin

g genes

provide

instruct

ions for

making

molecule

s called

transfe

r RNAs (

tRNAs) a

nd

ribosoma

l RNAs (

rRNAs),

which ar

e chemic

al cousi

ns

of DNA.

These ty

pes of R

NA help

assemble

protein

building

blocks

(amino a

cids) in

to funct

ioning

proteins

.

END