Forensic science

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TRACE EVIDENCE :

HOW CAN IT BE CLASSIFIED :
2 categories: Physical and Chemical

MICROSCOPES:

Differentes pieces: pointer,ocular,stage clip,arm,coarse adjustement,fine adjustement,body tube,nose piece,objectives,stage,illuminator.

[pic]

DETERMINING THE SIZE OF AN ORGANISM :
1.We must first know the size of the diameter of our field vision.(for each possible total magnification)2.Magnification: Diameter of field:

32x 5000um
100x 1750um
400x 400um

( - - - - - - - - - - ) ex: the cell is only taking 2 off 10 2/10 of the scale. Which means its 0.2

The diameter of field used was 1750.
You do: 0.2x1750= ANSWER

HAIR LAB 5#:

Root: make the difference between human andnon-human hair.

MEDULLA ET AUTRES :
[pic]

MEDULLA:
• Absent,fragmented,intermittent and continuous. (different patterns
• IS THE CENTRAL CORE

CORTEX:

• Determine color hair (CORtex=COLor)

• Contain melanin

• Largest portion of the hair

CUTICLE:
• Made up of dead,translucent cells STRENGTH OF THE HAIR
• Coronal,spinous or imbricate

HUMAN VS ANIMALS:HUMAN:
SCALE PATTERN:imbricate
HAIR TYPES: facial,limb,pubic ETC

ANIMAL:
SCALE PATTERN:spinous,coronal et imbricate.
HAIR TYPES : guard hair(outer coat)
Ground hair (underfur)
Tactile hair (whiskers.)
THESE ARE UNIQUES CARACTERISTICS WHICH HELP A LOT SCIENTIST IN THEIR RESEARCH!!

HAIR SAMPLES:

• It is impossible to perfectlylink hair samples to an individual.
• Class evidence

!ONLY WAY IS IF IT CONTAINS DNA. FOLLICULAR TAG!

MAKING A MATCH:

1.having +/- 50 hairs from the suspect
2.compare by looking at:
• Color,width,length
• Diameter
• Medulla
• Cortex
• Cuticle

FIBERS:
2 CATEGORIES: NATURAL AND MANMADE

CARACTERISTICS TO TAKE CARE OF:

Fiber type shapediameter color variation of color in the fiber

Length of fiber lengthwise striations of the fibers surface

COLLECTING FIBERS:

• Should be collected as soon as possible if not they may be lost
• Fibers are collecting by TAPING or by VACUUMING

COMPARING FIBERS:

• ANALYZED BY: diameter,shape,color,shininess,curls and crimps
• USED TOOLS:Birefringence: for synthetic fibers
Microspectrophotometry: determines a fibers true color
Polarized light: reflective index
Refractive index: refractive index
Scanning electron microscope: fine structural and surface details of damaged fibers

!ANALYSE CHEMICAL AND PHYSICAL CARACTERISTICS!!

GLASS:
• All glass can be different
•Broken glass provide information like:
-point of entry/exit
-what broke it
-fingerprints
-shoeprints
-DNA
SOILS AND PLANTS:
-Since plants grow in different areas, it decreases the size of a search of that specificacity

BLOOD:
-how blood moves and behaves under the laws of physics
-how blood behaves chemically
-molecular component found inside theblood

1)blood under laws of physics:
- will land in specific pattern :: velocity,size,angle WHEN DROPPING
PROVIDE GOOD ANSWERS TO QUESTIONS LIKE:
; Where did the blood come from
; What object caused the victim to bleed
; What direction did the object strike the victim from
; Where did the victim and assailant start,and where did they move to?
; How many strikes?( combien de coupures ?)2)blood chemicals
-Special proteins in the blood creates des caillots (clots) once it leaves the body
MORE TIME = MORE CLOTTING

Still liquid( minutes have passed
Jelly-shiny substance( up to an hour has passed
Separated into clot and serum( more than one hour has passed

3) Molecular component:
-Proteins
-Cells; DNA which is unique to every person
-Drugs,poisons and alcohol can also...
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