At autopsy 18 hours after death in a tropical climate (30°C), a body shows cadaveric rigidity that is well established. A small amount of purplish discoloration is noted on the face with a few gas-filled blebs on the skin. Lividity is fixed and well distributed on the back. What is the sequence and timing of postmortem changes that accounts for these findings?

• A Rigor mortis appears immediately after death; lividity takes 72 hours to fix; putrefaction starts at 6 hours
• B Rigor mortis: onset 1–2 hours, maximum at 12 hours; lividity: onset 30 minutes, fixed by 8–12 hours; early putrefaction: 24 hours in temperate climate, earlier in tropics ✓
• C Rigor and lividity develop simultaneously within 30 minutes; putrefaction starts at 48 hours in all climates
• D Putrefaction precedes rigor mortis in tropical climates; lividity never fixes at temperatures above 30°C

Explanation

The correct sequence and timeline: Algor mortis (cooling) begins immediately. Livor mortis (hypostasis) begins at 30 minutes to 2 hours, becomes fixed (non-blanchable) by 8–12 hours as HbO2 extravasates into tissues — therefore lividity fixed on the back confirms body has not been moved. Rigor mortis begins at 1–2 hours, is maximum (well established) at 12 hours, begins to resolve at 24–36 hours (in temperate climate). Putrefaction begins at 24–48 hours in temperate climates but is significantly accelerated in tropical conditions (30°C+), often starting within 18–24 hours — consistent with the early cutaneous discoloration and skin blebs described. High temperature markedly accelerates bacterial decomposition.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.