crime scene investigation
TRANSCRIPT
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