MT428 Module 2

Simple Microscope

magnifying glass

Compound Microscope

the basic microscope of forensic science; consists of objective lens and ocular/eyepiece lens

Parfocal

when the microscope is focused with one objective, the other objective can be rotated into position and the specimen will remain in focus

Illuminator

light source of a microscope

Condenser

focuses the light on a microscope

Objective Lens

first image forming component on the microscope

Ocular Lens

final image forming component of a microscope

Field of View

area that can be seen through the eyepiece of a microscope

Depth of Focus

thickness that can be clearly seen in a microscope

Magnifying Power

number is inscribed on each lens; the product of the ocular magnifying power x the objective magnifying power is the total magnification

Inverted

how images are viewed on a microscope

Comparison Microscope

basically two compound microscopes attached together with a series of mirrors and prisms; this allows the viewer to look at different objects side by side; the view can be emphasized from one side to the other

Stereomicroscope

magnifies generally from 10X to 125X; allows a 3D view of an object; objects are viewed as a right side up image

Microspectrophotometer

visible/UV; most labs exclusively use the visible spectrum; used to determine the color spectrum of a microscopic object; most commonly fibers and paint chips

FTIR

can be used to determine the chemical composition of fibers, plastics, and paint chips (frequently present in microscopic forms)

Forensic Biology

originally called forensic serology; involved the use of conventional serological techniques to determine the possible origin of body fluid stains

Modern Day Forensic Biology

uses tests that range from chemical tests from the 19th century to the molecular biology methods of the 80’s, population genetics and statistics of the 90’s and computer algorithms of the 20’s; used in conjunction with crime scene reconstruction and blood stain spatter interpretation

Major Crimes

homicide, assault, sexual assault, burglary/robbery (property crimes)

Homicide

conduct which causes of death of a person or an unborn child with which a female has been pregnant for more than 24 weeks under circumstances constituting murder, manslaughter in first or second degrees, criminally negligent homicide, abortion or self abortion in first degrees

Homicide Chargers

murder, manslaughter, criminally negligent homicide

Murder

with intent to cause death of another person, he/she causes the death of such person or a third person; first or second degree

Second Degree Murder/Manslaughter

recklessly causes the death of another person

First Degree Murder/Manslaughter

with intent to cause serious physical injury to another person, he causes the death of such person or a third person

Criminal Negligence

a person acts negligently with respect to a material element of an offense when he should be aware of substantial and unjustifiable risk; the failure to perceive this risk involves gross deviation from the standard of care that a reasonable person would observe in the same situation

Criminally Negligent Homicide

with criminal negligence, he or she causes the death of another person

Sexual Assault

rape, statutory rape, sodomy

Rape

penetration, no matter how slight, of the vagina or anus with any body part or object, or oral penetration by a sex organ of another person without consent of the victim; this may occur by the use of force or deception

Statutory Rape

instance of sexual intercourse between a man and a woman where the victim is below the age of consent and the perpetrator is above the age of consent

Sodomy

anal or oral copulation with the member of the same or opposite sex and there is no consent

Incidence of Rape

females account for 86% of the victims; males account for 14% of the victims; 38% of the victims received an injury in addition; 36% reported

Reasons Why Rapes go Unreported

personal matter, fear of reprisal, police bias

Lack of Consent

element of every sex crime; results from forcible compulsion, incapacity

Treatment of Minors

those who can give informed consent can consent to treatment for SA; cannot be forced to undergo exam; must be confidential (as it would be for any patient)

People Incapable of Consent

<17 years of age, intellectually disabled, mentally incapacitated, physically helpless; or committed to a state department of correctional services or a hospital and the assailant is an employee

Forensic Photography

creates a permanent record (because physical evidence is short lived)

Police Photographer

person of contact if bite marks are present on a victim; trained in extensive photography using scales and special lighting

Bite Mark Evidence Processing

photography prior to swabbing; collect swabs, using sterile de-ionized water; insert into dried secretions box and label

Drug Facilitated Sexual Assault

defined when victim lost consciousness or was under the influence during the attack; specimens must be collected ASAP (different kit than standard procedure); test urine and blood

Trace Evidence

primarily on clothing; clothing should be collected over examination table paper (laid on floor); collected in separate bags

Clothing Processing

collect anything the victim wore during immediately following the assault; each item should be individually packages in a paper bag; allow wet stains to air dry; do not use plastic bags for long term use; if anything needs to be cut off, do not cut through any obvious tears or holes

Fingernail Scraping Processing

scrape under each nail over a paper towel; use separate paper towels for each hand; include the stick

Pubic Hair Combings

collect over paper towel; place the comb onto paper towel; collect if possible, using as little trauma as possible; can be collected at a later date if required

Rape Kit Swab Handling

2 swabs for oral, anal, vaginal, and cervix; victim can refuse at any step

Additional Evidence Processing for Sexual Assault

examine the head hair and pubic hair of the victim for matting; ideally, cut off the hair and put in the debris collection envelope, label the source and reason for collection

Hospital’s Role Post-Rape Kit

maintain the kit until it is confirmed by the victim that she wants to have police involvement; new law mandates that kits be stored at a designated site for 20 years

Documentation of Evidence in the Lab

important first step; record condition of packaging, condition of evidence, stains present, test results; used to refresh analyst’s memory

Documentation of Evidence - Note Taking

each page must have the page number, case number, date and initials of analyst; should be legible and organized; use a single line with initials for cross outs

Collecting Samples in the Lab

assume that DNA typing will be done; use a clean cutting surface for each item, wear gloves; clean forceps using 5-10% bleach, follow with flame; use a clean scalpel for each item; photo document stains before removal; thoroughly describe the stain (location and size); use a clothing diagram to demonstrate the stain

Types of Biological Stains

blood, semen, saliva, urine, feces

Blood

composed of cellular components in a liquid matrix (red blood cells, white blood cells, platelets); anti-coagulated liquid portion is plasma; coagulated liquid portion is serum

White Blood Cells

DNA component of the blood (contain nuclei)

Platelets

cause clotting

Presumptive Tests for Blood

appearance, phenolphthalein, leuco-malachite green, luminol

Appearance of Blood

does not fluoresce under a monochromatic light

Hemoglobin

O2/CO2 carrier of blood, contains peroxidase activity

Phenolphthalein Test

Hb based reaction; very sensitive; phenolphthalin (blue) turns pink in the presence of Hb

Leuco-Malachite Green

turns blue when exposed to blood and H2O2

Luminol Test

used to detect occiut blood (especially after cleaned up); results in short-lived white light (must be used in the dark); cross reacts with many compounds (cleaning agents, metals)

Occult Blood

hidden samples

Species Identification

used to determine if blood is a human vs dog vs cow; uses antiserum based method or DNA based method

Antiserum Based Method

uses species specific antisera that precipitate; cannot determine human vs chimp or dog vs wolf, but can determine human vs dog

Ring Precipitin Test

an eluate of the bloodstream is layered over the antiserum in a small glass test tube; it is allowed to stand in the vertical position for 10 minutes; it is then examined for the presence of a thin white ring at the antiserum/eluate interface; it is best viewed using a bright light

Semen

tick, generally whitish secretion of the male reproductive organ; composed of sperm in secretions from the prostate gland, seminal vesicles, cowper’s gland. and the glands of littre

Acid-Phosphatase (ACP) Test

presumptive test for semen on filter paper; relies on the liberation of naphthol from sodium a-naphthyl phosphate by the A.Pase enzyme; naphthol then couples with buffered brentamine fast blue B to form a purple azo dye; cannot be used to determine the postcoital intervals

Specific Tests for Semen

microscopic examination and prostate-specific antigen

Visual Appearance of Semen

dried stains will appear crusty and stiff; will be white to yellow in color; will not be readily seen on all surfaces or materials; monochromatic light source can aid in the visualization of dried stains

Semen and Saliva

fluoresce under light sources

Acid Phosphatase

enzyme that has a high concentration in semen/blood

Confirmation of Semen

confirmed with 1 of 2 tests (microscopic search and PSA); slide is prepared by centrifuging the eluate and then smearing the pellet onto a glass slide; slides are stained with nuclear fast red/picroindigocarmine; slides are examined using a compound microscope

Acrosome

the defining feature for sperm under a microscope; clear head portion

Prostate Specific Antigen

liquifying enzyme and glycoprotein that originates from the prostate gland and is found in significant prostatic tissue and secretions from the prostate gland, including semen; small amounts can be found in the male blood but they are generally below level of detection; has been found to be present in some breast milk, breast tumors, glandular epithelium in the vagina and apocrine sweat glands

Seratec PSA Test

specifically used when a sexual assault perpetrator is sterile or has had a vasectomy; two side sandwich assay; uses labeled monoclonal mouse anti-antibody; binds to PSA in the sample and will then travel to the test region where it will bind to a second monoclonal antibody that is bound to the membrane, resulting in the formation of a red line

Saliva Identification

based on the detection of a large concentration of amylase; will fluoresce under a monochromatic light source

Salivary Amylase

responsible for the hydrolysis of of both straight and branched chain starches

Saliva Test

sandwich type antibody assay specific for human alpha salivary amylase (does not react with pancreatic amylase)

Feces

found in property type/vandalization/burglary crimes; assailants “leave their mark”

Identification of Fecal Material

done by noting the basic appearance (color, smell)

Confirmation of Fecal Stains

done by the microscopic observation of epithelial cells, plant cells, starch granules, striated muscle cells, and amorphous debris (common components)

Edelman’s Test

utilized to detect the presence of urobilinogen (breakdown product of hemoglobin metabolism) in fecal material

Urine Stains

will typically result in a discoloration of the fabric; not easily seen on clothing composed of dark colored material; some stains will emit a characteristic odor due to ammonia; will weakly fluoresce when exposed to alternate light source

Urea

major end product of protein metabolism; it is found in high concentrations in urine and in lower concentrations in tears, semen, serum, and perspiration

Creatinine

major excretion product found in high concentrations in the urine

Urine Identification

test of urea and creatinine

RSID

identification test for urine; detects tamm-horsfall protein

Tamm-Horsfall

most abundant protein in the urine; secreted by the kidneys in the loop of henle

Historical Methods of Forensic DNA

helpful in associating an individual with a crime scene, but not conclusive; did not work with with mixtures or have a high power of discrimination; ABO blood typing and isoenzyme electrophoresis

Forensic DNA Applications

conventional STR’s, Y-STR’s; mitochondrial DNA

DNA Use in Forensic Cases

looking for match between evidence and suspect/victim or evidence in one case to evidence in a different case

Challenges to DNA Use in Forensic Cases

mixtures must be resolved; DNA is often degraded; inhibitors to PCR are often present

6 Picograms of DNA

present in each diploid human cell

3 Picograms of DNA

present in each haploid human cell

1 Nanogram of Genomic DNA

contains 333 copies of each locus; 2 per 167 diploid genomes)

Gene

entire DNA sequence required for synthesis of a functional protein or RNA molecule; consists of exons and introns

Exons

coding regions of DNA

Introns

transcription control and non-coding regions of DNA; hypervariable regions (important in forensic DNA)

Genotype

a person’s genetic makeup

Phenotype

physical result of a genotype

Locus

the position that a gene or DNA marker occupies on a chromosome

Allele

one or more alternate forms of a gene that occupy a locus

Homozygous

identical alleles at a locus