Unit 5: Forensic Anatomy :. This unit will cover the various body systems that can be used for forensic identification in various criminal investigations. Body fluids Topics covered will include: blood, blood typing and identification and blood splatter analysis Hair analysis Fingerprints
This unit will cover the various body systems that can be used for forensic identification in various criminal investigations.
Serology is the examination and analysis of body fluids. A forensic serologist may analyze a variety of body fluids including saliva, semen, urine, and blood.
From 1950 to the late 1980’s, forensic serology was a most important part of lab procedures.
With the development of DNA techniques, more time, money, and significance was placed in developing DNA labs.
However, with limited funds and the time required for DNA testing, most labs still use many of the basic serology testing procedures.
Questions to be answered:
Larger nucleic red blood cells
1901 Karl Landsteiner discovered the ABO blood groups.
1915 Leone Lattes developed a method of typing dried blood stains.
The procedure is called the absorption-elutionmethod, and dried blood spots are collected using a cotton swab moisten with distilled water.,
O , B
A nor B
A and B
A, B, O, AB
A nor B
A, B, O, AB
A and B
A small piece of the fabric is cut off
The fabric is then put in a small container of normal saline (a water solution with the same salt concentration as the human body), and a few drops of anti-A and anti-B antibodies are added.
It is then placed in a container of freshsaline and heated to a temperature of 54°C for about 5 min.
This temperature is high enough to break the antibody-antigen bonds, and the antibodies are released into the saline solution.
Blood type can be determined
Based on the premise that all bloodstains and bloodstain patternsare characteristic of the forces that have created them.
1. Stain condition
Lab Results Reconstruction
1. Genetic marker typing
2. Age Determination
3. Source Determination
4. Race Determination
5. Sex DeterminationBlood Pattern Reconstruction
—From “Cracking Cases” by Dr. Henry C. Lee
A field of forensic investigation which deals with the physical properties of blood and and the patterns produced under different conditions as a result of various forces being applied to the blood. Blood, as a fluid, follows the laws of physics.
The shape of a blood drop:
The location of the blood source can be determined by drawing lines from the various blood droplets to the point where they intersect.
The area of convergence is the point of origin; the spot where the “blow” occurred. It may be established at the scene with measurement of angles by use of strings.
80% of the population are secretors. Their blood-type antigens are found in high concentration in their body fluids such as saliva, semen, vaginal secretions and gastric juice.
Blood released or thrown from a blood-bearing object in motion
Ex gunshot, coughing, sneezing or explosivesHigh Velocity
Saliva is becoming more and more useful as physical evidence. In the past, it was mostly used to determine blood type.
saliva from a secretor can be used to determine their blood type.
Evidence such as cigarette butts, chewing gum, bite marks, envelopes, and stamps should be packaged in clean paper or a paper bag. If the evidence is damp, it should be air-dried before packaging. Saliva residues can be removed from immovable objects using a moistened cotton swab.
In the case of sexual crimes one of the most important pieces of physical evidence for the investigator to discover is the presence of seminal fluid (semen)..
When the scene of a sexual crime is searched, it is customary to first try to locate any seminal stains.
Suspected stains can be tested using a piece of filter paper moistened with a solution of sodium naphthol phosphate or Fast Blue B. Both these chemicals change color on reacting with the acid phosphatase present in fluid.
“For three days after death, hair and fingernails continue to grow but
phone calls taper off.”
Comedian and television host
Human hair is one of the most frequently found pieces of evidence at the scene of a violent crime. It can provide a link between the criminal and the crime.
From hair one can determine:
If the source is human or animal
Origin of the location on the source’s body
Whether the hair was forcibly removed
If the hair has been treated with chemicals
If drugs have been ingested
HAIR IS A VERY PERSISTEN FORMOF PHYSICAL EVIDENCE
The follicle is fed by tiny blood vessels
Hair can be used for drug analysis because anything present in the bloodstream is also incorporated into the hair.
The protein of the hair is keratinized, which makes it very strong.
Human hair has 3 layers called the cuticle, cortex and medulla.
The cuticle is the outermost layer of hair.
The cuticles of different species display different patterns.
Forensic scientist can analyze the cuticle pattern of any hairs left at the crime scene to determine answers.
Cuticle—outside covering, made of overlapping scales
Cortex—inner layer made of keratin and imbedded with pigment; also contains air sacs called cortical fusi
Medulla—inside layer running down the center of the cortex
The cuticle is the outermost layer of hair which is covered with scales. The scales point toward the tip of the hair. Scales differ between species of animals and are named based on their appearance. The three basic patterns are:
In order to visualize the
paint clear fingernail polish on a glass slide
when the polish begins to dry, place a hair on the polish
when almost dry, lift off the hair and observe the scale imprints
What pattern is seen in
The cortex gives the hair its shape.
It has two major characteristics:
Melanin—pigment granules that give hair its color
Cortical fusi—air spaces, usually found near the root but may be found throughout the hair shaft
The medulla is the hair core that is not always visible. The medulla comes in different types and patterns.
Human medulla may be continuous, fragmented or absent.
Determined by measuring the diameter of the medulla and dividing it by the diameter of the hair.
Medullary Index for human hair is generally less than 1/3.
For animal hair, it is usually greater than 1/2.
Can be straight, curly or kinky depending on the cross-section, which may be round, oval or crescent-shaped
Anagen—hair that is actively growing; lasting up to 5 years
Catagen—hair is not growing; a resting phase
Telogen—hair that is dying and ready to fall out; lasting two to six months
Length—about 0.5 mm per day or 1 centimeter per month; approximately one half inch per month
Human roots look different based on whether they have been forcibly removed or if they are telogen hairs and have fallen out. Animal roots will vary, but in general have a spear shape.
Distribution, shape and color intensity of pigment granules
Dyed hair has color in cuticle and cortex
Bleaching removes pigment and gives a yellow tint
Presence or absence of medulla
Hair samples are matched using a comparison microscope
The root contains nuclear DNA. If the hair has been forcibly removed, some folicular tissue may be attached containing DNA.
The hair shaft contains abundant mitochondrial DNA, inherited only from the mother. It can be typed by comparing relatives if no DNA from the body is available. This process is more difficult and costly than using nuclear DNA.
Questioned hairs must be accompanied by an adequate number of control samples.
from possible suspects
from others who may have deposited hair at the scene
50 full-length hairs from all areas of scalp
24 full-length pubic hairs
Napoleon died in exile in 1821. By analyzing his hair, some investigators suggest he was poisoned by the deliberate administration of arsenic; others suggest that it was vapors from the dyes in the wallpaper that did him in.
This is a human head hair of Caucasian origin. Caucasian hairs come in the widest variety of colors, can be of fine to medium coarseness and are generally straight or wavy.
In addition, the shafts vary from round to oval in cross section. Finally, color pigments are fine- to medium-sized and are evenly distributed throughout the shaft
Photomicrograph of Caucasian Head Hair
Photomicrograph of Beard Hair Medulla (Doubled
This is a human head hair of Afro-Caribbean origin. Such hairs are generally curly or kinky, and have a flattened cross section.
Larger than those of other racial groups, its pigment particles are grouped in clumps of different sizes and shapes and may be so dense that they render the hair opaque.
Furthermore, the hair shaft may vary — or seem to vary — in diameter because of its flattened nature and the way it settles on the microscope slide.
Bleaching removes pigment from the hair and can give the hair a characteristic yellow cast
dyed hairs possess an unnatural cast or color. In addition, the cuticle will take on the color of the dye
This is a human head hair of Asian origin.
Such hair is generally coarse, straight and circular in cross section. Its diameter is wider than the hair of other racial groups, and the outer layer of the hair, the cuticle, is usually significantly thicker.
The medulla, or inner layer of cells, is continuous and wide.
In addition, the hair shaft contains pigment particles that are generally larger than those of Caucasian hairs, and often appear to be grouped in patchy areas.
Finally, the hair may have a reddish appearance, a product of its pigment
Humans have a very fine cuticle pattern, called imbricate, with overlapping shingles of cuticles always point toward the tip.
Animal hair often has much rougher cuticles, such as spinous or coronal.
Spinous cuticle patterns are found on the hair of cats, minks, seal but not on humans.
Coronal cuticle patterns are found on the hair of rodents and bats
Spinous or petal-like scales are found at the proximal region of mink hairs and on the fur hairs of seals, cats, and some other animals
left is mink, below is seal
Coronal scales are commonly found in the hairs of small rodents and bats but rarely in human hairs.
The imbricate or flattened scales type consists of overlapping scales with narrow margins.
They are commonly found in human hairs and many animal hairs
This is a deer hair. Unlike that of any other animal, the root of deer hair has a wine-glass shape: a narrow root that gradually widens.
In addition, the medulla, or inner layer of cells, consists of spherical cells that take up the whole width of the hair in a repeating pattern of different shapes, such as a hexagonal shape, depending on what member of the deer family the subject belongs to
This is a cat hair.
Cat hair has fibrous roots and its pigment particles do not run down to the root.
In addition, its medulla, or inner layer of cells, is thicker than that of dog hair
This is a dog hair.
Dog hair has spade-like roots and its pigmentation runs down throughout the shaft to the root.
Its medulla, or inner layer of cells, is thinner, too, than that of cat hair