Semester 2 Forensics Review

Unit 6: Death and Forensic Anthropology

Vocabulary

• Antemortem: Occurring before death

• Perimortem: Occurring at or near death

• Postmortem: occurring after death

Autopsy

• An autopsy is a medical exam of a body after death

• Autopsies ordered by the state can be done by a county coroner, who is not necessarily a doctor. A medical examiner who does an autopsy is a doctor, usually a pathologist. Clinical autopsies are always done by a pathologist

• Autopsies are done for several reasons, including the following:

  • When a suspicious or unexpected death occurs

  • When there’s a public health concern, such as an outbreak with an undetermined cause

  • When no doctor knows the deceased well enough to state a cause of death and to sign the death certificate

  • When the doctor, the family or legally responsible designee of the deceased person requests an autopsy

• Autopsy procedure begins with the general and ends with the specific

  • 1st, a visual exam of the body is done, including the organs and internal structures

  • Then, microscopic, chemical, and microbiological exams may be made of the organs and internal structures

  • All organs are removed for examination and are weighed, and a section is preserved for processing into microscopic slides

  • A final result is made after all the lab tests are complete

  • Autopsies may last 2-4 hours. The results of lab tests on samples of body fluids and tissues may take a few weeks to be returned

The Manner of Death

• The manner of death can be one of 5 categories:

  • Natural

  • Accidental

  • Suicide

  • Homicide

  • Undetermined

• Sometimes it is difficult to determine the manner of death

• The most common manner of death is natural

Cause and Mechanism of Death

• The reason for death is the cause of death (ex: death by gunshot)

• The specific change in the body that brought about the cessation of life is the mechanism of death (ex: bled out due to gunshot)

Time of Death: Livor Mortis

• The leaden- color of death

• When red blood cells break down, they turn a bluish-purple

• With decomposition, blood seeps down and settles in the lowest parts of a body

• The discoloration that accompanies this becomes permanent after 8 hours

• Warmth accelerates this process

Time of Death: Rigor Mortis

• The rigidity of death

• At death, skeletal muscles cannot relax

• Without oxygen, calcium accumulates in the muscles, which then become stiff

• Rigor mortis starts in the eyelids and jaw muscles, moves upwards through the rest of the face, and downwards to the muscles of the chest, upper limbs, abdomen, and lower limbs

• After about 15-36 hours, the muscle fibers begin to dissolve, and softening begins in the same order

Time of Death: Algor Mortis

• The chill of death

• In death a body no longer generates warmth and begins to cool down

• To find the standard temperature of a corpse, a thermometer is inserted into the liver

• The human body is typically 98.6 degrees F

• Body heat is lost at a rate of 1.4 degrees F for the first 12 hours

• Body heat is lost at a rate of .7 degrees F after the first 12 hours

• The maximum loss of 16.8 degrees F can be lost during the first 12 hours

• Subtract the average body temp (98.6) by the body’s new temp and if it is less than 16.8 it has been less than 12 hours since death, if more than 16.8, it has been longer than 12 hours. Then, if it has been less than 12 hours, divide the number by 1.4 and the answer is how long the body has been dead for. If it has been more than 12 hours, subtract the number by 16.8 and divide the answer by .7, then add 12 hours to the answer to find out how long the body has been dead for.

Time of Death: Stomach and Intestinal Contents

• If food is present in the stomach, then death occurred 0-2 hours after the last meal

• If the stomach is empty, but food is found in the small intestine, death occurred approximately 4-6 hours after the last meal

• If only wastes are found in the large intestine, death occurred 12+ hours after the last meal

Time of Death: Potassium Eye Levels

• There is fluid within the eye called vitreous humor

• A sample should be taken from one eye immediately, a second sample should be taken from the other eye an hour or two later

• After death, the cells in the eye release potassium into the eye fluid

• Scientists use the rate at which potassium is released to approximate the time of death

• This is dependent on ambient temperature

Time of Death: Stage of Decomposition

• Within two days after death:

  • Cell autolysis begins following death

  • Green/purplish staining occurs from blood decomposition

  • The skin takes on a marbled appearance

  • The face becomes discolored

• After 4 days:

  • Skin blisters

  • Abdomen swells with gas as CO2 is released from intestinal bacteria

• Within 6-10 days:

  • Corpse may burst from build up of gas

  • Fluids begin leaking from body openings

  • Eyeballs and other tissues liquify

  • Skin falls off

Time of Death: Insects

• Besides recording data about the environment at a crime scene, a forensic entomologist collects insect evidence

• Within minutes of a death, certain insects arrive to lay their eggs on the warm body. Blowflies are a common example

• As a corpse progresses through the stages of decomposition, other kinds of insects arrive

  • Blowfly eggs can be found in the moist, warm areas of a corpse within 8 hours after death

  • They will have progressed to the 1st of their 3 larva stages within 20 hours

  • Around 2.5 days, they will be in their 2nd larval stage

  • By the 4th or 5th, they will have progressed to the 3rd of their 3 larval stages

  • By the 8th or 12th day the larvae will migrate away from the corpse to a dry place

  • Becoming a pupa and immobile within 18-24 days, they will change from white to dark brown

  • By the 21st -24th day, the pupa cases will split open and adult blowflies will emerge

• Because scientists know how long it takes for the various stages of development at given temps, forensic entomologists can determine when the insects arrived

• Because life cycles are affected by fluctuations in the daily environmental conditions, insect evidence cannot provide an exact time of death

• Insect evidence, nonetheless, can yield a close estimate

Forensic Anthropology: Historical Development

• In the 1800’s, scientists began studying skulls. This laid the framework for today’s knowledge

• In the 1932, the FBI opened up the first crime lab

• The Smithsonian Institution became its working partner in the identification of human remains

• Soldiers killed in WW2 were identified using anthropologic techniques

Development of Bones

• Bones originate from osteoblasts

• They migrate to the center of cartilage production and deposit minerals

• Throughout life, bones are being broken down, deposited, and replaced

• Osteoclasts, the 2nd type of bone cell, among other tasks, remove cellular waste

How Bones Connect

• Bones are connected by:

  • Cartilage: wraps the ends of bones and keeps them from scraping one another

  • Ligaments: bands that connect two or more bones together

  • Tendons: connects to muscle to bone

• Until about 30 years of age, bones increase in size

• Deterioration after 30 can be slowed with exercise

What Bones Can Tell Us

• Osteobiography tells much about a person through the study of a skeleton

• The bones of a right-handed person, for example, would be slightly larger than the bones in the left arm

• Forensic scientists realize bones contain a record of a physical life

• Analyzing bones can reveal clues to such things as age, sex, height, and health

Skull Sex Determination

Pelvis Sex Determination

Age: Cartilaginous Lines

• During life, many of the 450 bones a person has at birth grow together, finally forming 206 bones

• As cartilage between them is replaced, an epiphysis line is visible

• When cartilage is fully replaced, the line is no longer visible

• This info can be used to approximate a skeleton’s age

Age: Suture Marks

• By about age 21-30, the lambdoid suture will have closed

• By about age 30-32, the sagittal suture will have closed

• By about 48-50, the coronal suture will have closed

Age: Teeth

• As human beings grow up and get older throughout life, teeth grow, change, and pass through different stages. Each of these stages has certain unique characteristics which can help determine a person’s approximate age

• In some cases, the tooth stage is visible to the naked eye while in other cases a microscope or x-ray is needed

• Once a tooth erupts (breaks through from the jaw bone), it starts to build two layers of hard tissue called cementum around its root each year

• If a cross-section of the tooth root is examined under a microscope, these layers appear as light and dark rings, similar to tree rings

• Scientists can count the number of layers and, if they add the eruption year, they will get the person’s age at death

• Scientists can also preform special chemical tests on teeth to determine a person’s age

Height

• Just as age can be estimated by looking at the bones of the arms and legs, so also can an estimate of height be made

• Often, the approximate height of a person can be calculated from one of those long bones even if just one is found

• Sex and race will need to be taken into consideration in making the estimate

• Will be given the formulas

Ancestry

• Determination of ancestry from skeletal remains is difficult. Generally, the following characteristics can vary by ancestral groups:

  • Shape of eye sockets (oval, circular, square)

  • Absence or presence of a nasal spine

  • Nasal index: Ratio of width of nasal opening to the height of the opening x100

  • Prognathism: projection of upper jaw beyond the lower jaw

  • Width of face

  • Angulation of the jaw and face

Unit 7: Soil and Impressions

Soil Introduction

• Factors such as temperature, rainfall, and the chemicals and minerals in the soil influence the production of soil

• Soil from different locations can have different characteristics (physical and chemical)

• Because of this, soil analysis has been helpful in such things as linking suspects to crime scenes and locating burial sites

History of Forensic Soil Examination

• Dr. Hans Gross is believed to be one of the first to recognize the importance of physical evidence

• His book, Criminal Investigation, written in 1893, had ground-breaking material in this science

• George Popp is credited with being the first to use soil evidence to solve a crime

  • He linked soil samples found on a suspect with samples found at a crime scene

Soil Composition

• Soil is part of the top layer of the Earth’s crust

• It contains minerals, decaying organisms, water, and air in varying amounts

• Soil texture describes the size of the mineral particles that make up soil

• The 3 main grain sizes are sand, silt, and clay

• The 3 sub categories of soil of loam, peat, and chalk

Soil Profiles

• Soils are formed in layers (horizons):

  • Humus, the O horizon, is made of decaying organic matter

  • Topsoil, the A horizon, is a mixture of humus and minerals

  • Sand and silt make up the E horizon

  • Subsoil, the B horizon, is made of clay and minerals

  • Broken rock, the C horizon, has very little humus horizon

  • Solid rock makes up the R horizon

Chemistry of the Soil

• An important chemical property of soil is whether it is acidic or basic

• Materials that make up a soil are not only factors that its pH level

  • Rainfall can change the pH value of soil

  • Pollution and fertilizers can also change the pH value of soil

• The pH of a soil sample can help a forensic scientist match it to other samples

Sand

• The action of wind and water on rocks form sand

• This may take millions of years

• Because water acts as a buffer, water produces sand more slowly than wind

• Wind-blown sand becomes rounded more quickly because the grains strike each other directly without a buffer

Mineral Composition of Sand

• Sand from different locations contains different combinations of minerals

• The most common mineral found in sand is quartz

• Other minerals may be found in smaller quantities

• Grains of sand may be rounded or angular depending on the amount of weathering and mineral composition of the grains

• Other than quartz, mineral contents of sand can include:

  • Feldspars

  • Micas

  • Iron compounds

• Sand can also be made of organic material such as coral and seashells

Continental sand and volcanic sand:

Skeletal and precipitate sand:

• Skeletal sand gives off bubbles when mixed with an acid

Soil Examination

• The presence of soil unique to a certain area can show that a victim or suspect must have been in that area

• Layers of soil or sand taken from shoes or the wheels of vehicles can show a suspect was present at a series of locations

• The following are useful in the examination of soil samples:

  • Looking at samples macroscopically

  • X-ray diffraction

Introduction to Casts and Impressions

• People, vehicles, and objects leave evidence of their presence at an accident or crime scene

• Patent Impressions: 2 dimensional

• Latent Impressions: hidden to the naked eye

• Plastic Impressions: 3 dimensional

Shoe Impressions

• The size of a shoeprint can tell us the size of foot of a person

• The depth of a foot or shoe impression can tell something of the person’s weight

• The type of shoe can tell something of the person’s job or personality

• Databases contain the names of specific manufacturers, and tread patterns used to identify different types of shoes

Shoe Wear Patterns

• Some factors that personalize a person’s footwear include:

  • Bodyweight

  • The way a person walks

  • The surface that the person usually walks

  • Debris that became embedded in the tread or unique holes and cuts in the tread

Collection of Shoe Impression Evidence

1. Take photos ASAP

2. Take multiple photos of the impression from at least 2 different orientations

3. Place an identifying label and a ruler in position with the impression for the photo

4. Use oblique lighting when possible

Lifting Latent Prints

• Different methods to make latent prints visible include:

  • Luminol will make bloody footprints visible

  • Dusting the latent prints reveals an impression

  • Electrostatic lifting and gel lifting techniques also can capture hidden impressions

Electrostatic Dusting and Lifting

• Electrostatic dusting can reveal dust left with each step and create an impression

• Electrostatic charges can lift impressions from paper, carpeting, wood surfaces, linoleum, asphalt, and concrete

• Other methods to recover latent impressions include gel lifters

• These methods can provide information about the person who left the shoeprint

Tire Treads and Impressions

• To channel water away and provide traction, a tire’s tread is divided into ridges and grooves

• Tires can also leave patent, latent, or plastic impressions

• Tire evidence usually indicates the type of vehicle that left the mark, may be used to link a suspect or victim to a crime scene, and can reveal the events that took place

Recording Tread Impressions

• Ridges and grooves of discovered tire impressions are counted across the entire width

• Unique wear characteristics such as wear or pebbles embedded in the grooves are noted

• A print of the suspect’s tire impressions (through 1 revolution) is taken

• Comparison with impressions from the crime scene, then, can be made

Identifying a Vehicle

• Identifying tread patterns may not be enough to link a suspect with a crime scene. Other things that can help with this:

  • Front and rear track widths

  • Wheel based measurements

  • Turning diameters

• Databases can be checked to find the vehicle with these specifications

Accident Reconstruction

• Drivers may not recall the exact series of events before, during, and after an accident

• People, vehicles, and objects, however can leave evidence of their actions at the scene of an accident

• Debris patterns and tire marks, for examples, can be clues to speed, direction, and vehicle identification

• There are 3 basic types of tire marks:

  • Skid marks: can be clues to distance when brakes were applied and the vehicle’s speed

    • Made when drivers slam their brakes

  • Yaw marks: Can how a sideways skid

    • Made when drivers lose control of their car

  • Tire scrub: Can determine area of impact

    • Made when the car hits something

Dental Impressions

• Occasionally, perpetrators will leave behind a bitemark

• Differences in size of teeth and jaws, position, crowns, caps, fillings, breakage, and crowding make bite marks individual evidence

Dental Patterns in Forensics

• The investigation consists of identifying, documenting, collecting, and analyzing evidence

• Up to 76 points of comparison can be used when comparing a suspect’s dental patterns with bite marks left at a crime scene

• We can use both bite marks and the teeth of corpses/skeletons in forensic investigations

Unit 8: Tool Mark Evidence

Unit 9: Handwriting, Forgery, Counterfeiting, and Glass

Handwriting, Forgery, and Counterfeiting Introduction

• Document analysts examine and compare questioned documents with known material

• Experts in the field investigate such things as handwriting, computer printouts, commercial printing, paper, and ink

• They may study threatening, ransom, or suicide notes

• Their work can help identify a document’s author

History of Forensic Handwriting Analysis

• In the 1930’s, handwriting analysis played a large role in the famous Lindbergh case

• In 1999, the United States Court of Appeals determined that handwriting analysis qualified as a form of expert testimony

• To be admissible in court, however, scientifically accepted guidelines must be followed

• Handwriting analysis has been used by Scotland Yard, the FBI, and the Secret Service

Natural Variants in Handwriting

• Everyone’s handwriting shows natural variations

Handwriting Examination

• Two handwritings are the product of one person if their similarities are unique and no explainable differences are found

• 1. Examine the questionable document for detectable traits and record them

• 2. Obtain some writings of a suspect (called an exemplar) and compare the traits found in the questionable document with it

• 3. Draw conclusions about the authorship of the questionable document based on the comparison