Forensic Exam (Death Investigation)

What is death investigation?

Process of determining who died, cause, manner, and time of death using medicine, biology, chemistry, law, and CSI.

Who are forensic pathologists?

Medical doctors trained to investigate deaths; work in medical examiner/coroner offices handling sudden, unexpected, violent, or suspicious deaths.

Main responsibilities of forensic pathologists

Perform autopsies, determine cause and manner of death, estimate PMI, review history, examine evidence, write reports, testify in court, teach/research.

What is an autopsy?

Careful medical examination of a body after death to find cause, look for injuries, collect evidence, and confirm manner of death.

Types of autopsies

Clinical (hospital): studies disease, not usually criminal. Forensic/medicolegal: determines cause and manner of death, collects legal evidence.

External examination in autopsy

Measure/weigh body, document appearance, check rigor/lividity, examine clothing/fingernails, collect trace evidence, remove vitreous fluid.

Internal examination in autopsy

Open body, examine and weigh organs, check for trauma/disease/bleeding/infection, return organs, suture body closed.

Cause of death

Physical injury or disease that started chain leading to death (e.g., blunt/sharp force trauma, asphyxia, gunshot, overdose, disease).

Manner of death

Legal classification explaining how the cause occurred: homicide, suicide, accidental, natural, undetermined.

Estimating time of death - Algor Mortis

Cooling of body 1–1.5°F per hour after death; starts ~1 hour postmortem.

Estimating time of death - Rigor Mortis

Stiffening of muscles 4–6 hours after death, fully by 12 hours, disappears 24–48 hours; indicates time since death and body position.

Estimating time of death - Livor Mortis

Blood pooling in lowest parts, causes lividity; shows body position; blanching occurs if pressure applied.

Putrefaction

Decomposition of tissues by bacteria/enzymes 3–4 days after death; skin blisters, color changes, gas buildup; helps estimate later time since death.

Other indicators of time of death

Vitreous humor potassium increases over time, cornea cloudiness, stomach contents digestion progress.

Forensic entomology

Study of insects on bodies to estimate time since death; blowflies/flesh flies arrive in predictable order; stage development shows PMI.

Forensic anthropology

Study of skeletal remains to determine age, sex, ancestry, height, trauma timing (antemortem, perimortem, postmortem); helps reconstruct events.

Key terms to know

Autopsy, PMI, cause of death, manner of death, rigor mortis, livor mortis, algor mortis, putrefaction, vitreous humor, antemortem/perimortem/postmortem.

DNA paper goal

Predict likelihood of successful DNA profiling on decomposed bodies to avoid wasted testing.

DNA paper method

Studied soft tissues from 69 decomposed bodies; developed Rot Score (Sp) for decomposition and DNA Quality Score (Si) for DNA integrity.

DNA paper findings

Kidney tissue has best DNA quality; more decomposed bodies (higher Sp) have lower DNA quality; Sp < 6 predicts successful standard DNA profiling.

DNA paper conclusion

Scoring system helps forensic scientists decide which tissue to test and whether standard DNA testing will likely succeed or fail on decomposed bodies.