Unit EForensic Medicine

What is Forensic medicine?

• Latin word –forensics

• Means public discussion or debate

• Science used in justice system for legal purposes

• Facts based on scientific investigation

• Goal is to determine facts and truth

• Uses multiple science specialties

Forensic Scientists

• Television enhances the image of forensic science….not always accurate

• Forensic scientists are involved in all aspects of criminal cases.

• The forensic scientist's goal is to use all available scientific information to determine the facts and, subsequently, the truth.

• The forensic scientist might determine: – The validity of a signature on a will, – If a corporation is complying with environmental

laws, – The origin of physical evidence at a crime scene

Document Examination

• This discipline involves all special relationships that may exist between document and inscription and how it relates to a person or sequence of events.

• This includes forgery, counterfeiting, and handwriting analysis.

Firearms and Toolmarks

• Typically, this includes matching bullets to the gun that fired them.

• Toolmark identification involves the identifying characteristics between tools, such as a pry bar, and the object on which it is used, such as a door frame.

• Also included in the category are explosives and imprint evidence.

Techniques and examples

• Autopsy- earliest technique

• DNA typing - most recent

Techniques and Examples

• Forensic anthropology• Odontology: the proper examination,

handling and presentation of dental evidence in a court of law

• Blood testing

Autopsies

A. Definition and Purpose• Postmortem examination• Used to determine the cause of death and

how the person died.

Autopsies

B. Legal Requirements

1. Coroner- a public official who investigates sudden, suspicious, or violent death to determine the cause - Coroner’s office is responsible for conducting autopsies

2.Medical examiner - a physician who is appointed by a state or local government to establish the cause of somebody's death, especially in cases where death is not the result of natural causes.

3. Pathology -the scientific study of the nature, origin, progress, and cause of disease…examines tissues, fluids, etc.

C. Reason for autopsy

1. Determine what disease or injury caused death

2. Medical Diagnosis- confirmation and understanding

3. Evaluate possible public health issue

D. Preparation

1. If not required by law, permission needed from next of kin

2. legal consent form

E. Procedure

1. First – Examine complete medical history and review of records

2. External physical exam

a. body tag

b. weight and height

c. examine clothing and valuables

d. document scars, tattoos, injuries, wounds, bruises

e. foreign objects noted (i.e. piercings, knives, protruding shovel, etc.)

3. Photos and x-rays taken, if needed

4. Complete internal exam

a. dissection of head and abdomen

b. organs removed, weighed, measured, and examined

c. tissue samples examined under microscope

d. fluid samples tested for drugs, infection

5. After autopsy complete, legal death certificate completed

F. Results

1. Natural death- disease or old age

2. Unnatural death- unexpected, or unusual cause

G. Methods of determine time of death

1. Traditional indicators

a. rigor mortis (stiffening of the muscles of the body after death)

- begins three hours after death in face and eyelid muscles

- takes twelve hours to affect entire body

- process reverses after 36 hours

2. Lividity (hypostasis)

a. visible after 30-60 mins

b. red cells settle and skin below turns red

c. in 6-10 hours, color becomes permanent

3. Body temperature

a. falls at rate of approximately one degree per hour

b. obesity and warm environment slows cooling

Using body temp to determine time of death is not totally reliable and can be manipulated

DNA typing and Forensic Anthropology

A. DNA typing

1. What is DNA?

a. nucleus of cells contain RNA/DNA

b. DNA – deoxyribonucleic acid

c. nucleus has 23 pairs of chromosomes made up of DNA

d. within each pair, one chromosome from sperm and one from egg

2. What makes DNA individual?

a. Four chemicals- adenine, guanine, cytosine, and thymine

b. Chemicals strung together = DNA code

c. Some sections of DNA vary from individual to individual

d. Scientists can link a strand of DNA to a given individual

3. Criminal investigations

a. specimens: blood, hair, bloodstained clothing

b. provides powerfully compelling evidence

B. Forensic anthropology1. Skeletal Anatomy

a. 206 bonesb. Man = 12 pounds, woman = 10 pounds

2. What bones showa. How person livedb. Debilitating

illnesses (rickets, polio, healed fractures, osteoporosis)

c. Right or left handedd. Clues to

occupation

3. Questions answered with full skeletal remains

a. age of person at time of death

b. sex of person (skull and pelvis)

c. race (skull)

d. height

Odontology and Serology Studies in Forensic Medicine

A. Odontology

1. Characteristics of teeth after death

a. no other part of body lasts longer

b. in fires, teeth usually only means to ID remains (i.e. after 9/11/01)

c. no two people have identical teeth

2. Requirements for identification

a. needs dental records

b. dentists chart five surfaces of each tooth in a grid (odontogram)

c. can also provide “bite mark” evidence

3. Teeth useful in determining subject’s age

B. Serology

1. Blood type

a. Four types (A, B, O, and AB)

b. Rh factor – protein…if you have it you are Rh + if you don’t you are Rh -

c. female blood cells have Barr Body…so you can tell if a blood sample is from a male or female

2. Criminology

a. Kastle-Meyer test to determine if it is indeed blood

b. Precipitin test – determines animal or human blood

c. You can determine blood type and gender from blood specimen

d. Provides reliable and informative evidence