DiMaio Chapter 2: postmortem changes

Question 1

Name the three classic early postmortem changes

Answer 1

Livor mortis, rigor mortis and algor mortis (body temperature).

Question 2

Besides early changes, list two later postmortem processes discussed.

Answer 2

Decomposition (putrefaction/mummification/adipocere) and insect/animal activity.

Question 3

Which postmortem change can help indicate if a body was moved?

Answer 3

Both livor mortis (lividity patterns) and rigor mortis can suggest movement.

Question 4

Why does Chapter 2 caution against rigid time‑since‑death formulas?

Answer 4

Wide biological and environmental variability undermines precision.

Question 5

Typical onset window for rigor mortis in temperate conditions?

Answer 5

Begins ~2–4 h after death; fully develops by 6–12 h, with wide variability.

Question 6

Sequence of appearance/disappearance of rigor mortis in classical teaching?

Answer 6

Appears first in small muscles (jaw), then upper → lower extremities; passes off in the same order.

Question 7

Effect of decomposition on rigor mortis?

Answer 7

Rigor disappears as decomposition advances.

Question 8

Two factors that can accelerate development of rigor mortis.

Answer 8

Hyperthermia/fever and convulsant poisons (e.g., strychnine).

Question 9

Why can drowning victims show rapid, full rigor in 2–3 hours?

Answer 9

ATP exhaustion from violent struggling while drowning.

Question 10

Why might runners chased prior to death show early leg rigor?

Answer 10

Local ATP depletion in leg muscles from exertion.

Question 11

Can rigor mortis be used to estimate time of death precisely?

Answer 11

No—variability is too great; use cautiously for movement clues.

Question 12

How can rigor indicate a body was moved?

Answer 12

Inconsistent body position and stiffness vs. gravity and scene (e.g., elevated limbs).

Question 13

Name a case example where rigor persisted unusually long.

Answer 13

A drowned teen recovered after 17 days in cold water still in full rigor mortis.

Question 14

What happens if rigor is forcibly broken?

Answer 14

It does not return in the stretched muscles.

Question 15

State the simplest rectal‑temperature formula listed in the chapter.

Answer 15

Time since death (hours) ≈ 37°C − rectal temperature (°C) divided by 3.

Question 16

What classic equation converts Fahrenheit readings for PI estimation?

Answer 16

Glaister equation: (98.6°F − rectal temp °F)/1.5 ≈ hours since death.

Question 17

Why is assuming ‘normal’ body temperature problematic?

Answer 17

Normal varies by person, sex and time of day; modern mean ~98.2°F, not a fixed 98.6°F.

Question 18

Name two physiologic states that can elevate premortem body temperature.

Answer 18

Strenuous exercise and infection.

Question 19

In what circumstance might body temperature rise after death?

Answer 19

Early decomposition can increase temperature.

Question 20

Define adipocere and list its main chemical components.

Answer 20

A wax‑like postmortem change of fat—oleic, palmitic and stearic acids.

Question 21

Environments that favor adipocere formation?

Answer 21

Water immersion and damp, warm settings.

Question 22

Two last organs to decompose commonly cited.

Answer 22

Uterus and prostate.

Question 23

How quickly can skeletonization occur in exposed conditions?

Answer 23

As fast as 9–10 days, occasionally faster, depending on environment/scavengers.

Question 24

What postmortem fluid may be seen early from nose/mouth without clinical significance?

Answer 24

Bloody purge fluid from early decomposition.

Question 25

Define mummification contextually.

Answer 25

Rapid dehydration in hot, dry climates leading to leathery skin and preserved outlines.

Question 26

Decomposition quick fact 24: Does embalming guarantee long‑term perfect preservation?

Answer 26

No—results vary with embalming quality, climate and burial conditions.

Question 27

Most common insects on decomposing bodies and typical oviposition sites?

Answer 27

Blowflies; orifices and open wounds.

Question 28

If only eggs are present and the body hasn't been moved, what rough PMI can be inferred in daytime?

Answer 28

~1–2 days, but highly variable by species and environment.

Question 29

Approximate times: larvae to pupae, then adult emergence under ordinary conditions?

Answer 29

Pupation in ~6–10 days; adults emerge ~12–18 days after oviposition—both highly variable.

Question 30

Why caution against solo entomologic PMI estimates?

Answer 30

Species/temperature/humidity dependence—consult a forensic entomologist.

Question 31

Entomology quick check 1: Do blowflies usually lay eggs at night?

Answer 31

No—typically daytime oviposition.

Question 32

What historical vitreous K⁺ PMI method is discussed and why is it unreliable?

Answer 32

Sturner & Gantner’s PMI formula; variability grows with PMI due to decomposition effects.

Question 33

How does elevated ambient temperature affect vitreous K⁺ rise?

Answer 33

Accelerates decomposition → faster K⁺ increase.

Question 34

Why are DNA/RNA/protein degradation clocks not ready for routine PMI?

Answer 34

Assay variability and limited access to specialized equipment.

Question 35

Vitreous quick check 1: Is vitreous potassium a precise clock for PMI?

Answer 35

No—too variable across conditions/species differences and decomposition rates.

Question 36

What do radioisotopic gastric studies reveal about water vs solids emptying?

Answer 36

Water empties rapidly/exponentially, independent of solid meal; calorie‑containing liquids empty slower.

Question 37

How do meal weight and calories influence emptying?

Answer 37

Heavier meals increase emptying rate (g/min) but higher calories slow overall emptying.

Question 38

Why is using stomach contents to estimate PMI discouraged?

Answer 38

Large intra‑ and inter‑individual variability even with standardized meals.

Question 39

Gastric emptying quick check 1: Does knowing 'last meal time' yield a reliable PMI?

Answer 39

No—emptying is highly variable.

Question 40

Gastric emptying quick check 16: Does knowing 'last meal time' yield a reliable PMI?

Answer 40

No—emptying is highly variable.

Question 41

What is often the most reliable PMI bracket according to the chapter?

Answer 41

Interval between last seen alive and found dead, refined by scene markers.

Question 42

List three practical scene markers for narrowing PMI.

Answer 42

Recent texts/calls, uncollected mail, lights on/off, food out, receipts, routine disruptions, witness statements.

Question 43

Scene marker quick check 1: Are digital communications useful for PMI bracketing?

Answer 43

Yes—timestamps on texts/calls often help narrow the interval.

Question 44

Why are visual identifications considered non‑scientific?

Answer 44

Subject to error, deception and impossibility in trauma/decomposition.

Question 45

What scientific identification requires antemortem prints and databases like AFIS?

Answer 45

Fingerprint comparison.

Question 46

Name two circumstantial identifiers that support a presumptive ID.

Answer 46

Wallet/phone entries, jewelry, distinctive tattoos/scars, car registration, home ownership.

Question 47

ID quick check 21: Can degloved/mummified hands still yield prints?

Answer 47

Yes—rehydration and gloving techniques can recover usable prints.

Question 48

Preferred method after fingerprints/visual fail in burned or decomposed bodies?

Answer 48

Dental identification using charts and X‑ray comparisons.

Question 49

Does dental ID require fillings?

Answer 49

No—root morphology and sinus/tooth anatomy can suffice.

Question 50

What key limitation does dental ID share with fingerprints?

Answer 50

Requires antemortem records for comparison; no universal 'dental database'.

Question 51

What other medical imaging can provide a positive ID?

Answer 51

Comparison of postmortem to antemortem radiographs showing skeletal or soft‑tissue features.

Question 52

How can implanted hardware aid identification?

Answer 52

Unique lot/serial numbers on pacemakers/orthopedic devices trace to patient records.

Question 53

What is a common use of DNA in identification even when other methods succeed?

Answer 53

Confirmatory testing.

Question 54

DNA ID quick check 1: What must always be available for DNA comparison?

Answer 54

A suitable reference sample (relative or personal item known to be the decedent’s).