Forensic Medicine: PMI Estimation (Henssge, Newton, Vitreous K+)
Published:
Reviewed by Bismith B · 09 Jun 2026
Questions
30
Duration
30 min
Faculty-reviewed
0
Updated
26 May 2026
About this mock
This set drills the quantitative and semi-quantitative methods used to estimate post-mortem interval (PMI) in forensic medicine. Newton's Law of Cooling underpins algor mortis-based estimation: rectal temperature falls from 37 degrees Celsius toward ambient at a rate governed by body mass, clothing, and environmental conditions, and the Henssge nomogram (1988, Forensic Science International) converts rectal temperature, ambient temperature, and body weight into a 95%% confidence interval for PMI, with body-weight correction factors (Cf) for clothing, substrate, and air movement. Vitreous humour potassium (K+) rises post mortem through ion-pump failure, and the Madea formula (PMI in hours = 5.26 x [K+] mmol/L minus 30.9) provides a chemical PMI estimate usable up to 120 hours, with a coefficient of variation of roughly plus or minus 15 hours. Gastric emptying (2 to 6 hours for a mixed meal) frames last-meal timing. Rigor mortis passes through onset, full rigidity, and resolution in 8 to 36 hours in temperate conditions; Indian tropical heat compresses this cycle significantly. Livor mortis becomes fixed (non-blanchable) between 8 and 12 hours, providing a body-position marker. Putrefaction begins at the right iliac fossa within 24 to 48 hours in Indian summer climates. Adipocere and mummification are long-PMI markers seen in weeks to months. Entomological PMI uses accumulated degree days (ADD) on blowfly life-cycle tables. BNSS 2023 Section 194 (replacing CrPC Section 174) governs inquest procedure and PM timing.
Aimed at UGC-NET Forensic Science Paper II candidates targeting Unit X (Forensic Medicine), AIIMS Delhi and NFSU MSc students, MBBS candidates preparing for legal medicine, and CFSL and state medico-legal officers.
Topics covered:
- Newton's Law of Cooling and algor mortis: rectal temperature fall rate and influencing factors
- Henssge nomogram 1988: body weight, rectal and ambient temperature, correction factor Cf
- Vitreous K+ Madea formula: PMI = 5.26 x [K+] minus 30.9, range and error margins
- Gastric emptying as a PMI clock: 2-6 hours and forensic caveats
- Rigor mortis timeline in Indian climate: compressed cycle in tropical heat
- Livor mortis fixation: 8-12 hours and body-position change detection
- Putrefaction onset at right iliac fossa: 24-48 hours
- Adipocere and mummification: long-interval PMI markers
- Entomological PMI: accumulated degree days (ADD) method
- BNSS 2023 Section 194 inquest procedure and PM timing
Allow 30 minutes.
Sources & references
Questions in this mock are written and verified against the following sources. Citations are recorded per question and shown in the explanation after submission.
- cited in 9 questions
Knight, Bernard and Saukko, Pekka -- Knight's Forensic Pathology, 4th Edition, CRC Press
Chapter 2: Post-mortem changes -- livor mortis: mechanism, blanchability, fixation timing, and forensic significance as body position indicator
- cited in 7 questions
Modi, J.P. -- Modi's Medical Jurisprudence and Toxicology, 24th Edition, LexisNexis
Chapter: Post-mortem changes -- rigor mortis: Nysten law, craniocaudal sequence, ATP depletion mechanism, and PMI correlation
- cited in 3 questions
Henssge, Claus -- Death Time Estimation in Case Work, Part I: The Rectal Temperature Time of Death Nomogram, Forensic Science International, 1988
Correction factor Cf: clothing, substrate, and air movement adjustments to effective body weight in the nomogram
- cited in 3 questions
Spitz, Werner U. and Spitz, Daniel J. -- Spitz and Fisher's Medicolegal Investigation of Death, 4th Edition, Charles C Thomas
Chapter: Post-mortem examination -- gastric emptying caveats, stress-accelerated motility, and interpretation of stomach contents in violent death
- cited in 3 questions
Vij, Krishan -- Textbook of Forensic Medicine and Toxicology, 6th Edition, Elsevier
Chapter: Post-mortem changes -- rigor mortis in Indian tropical climate: temperature effects on ATP depletion and decomposition
- cited in 2 questions
Madea, Burkhard -- Potassium in Vitreous Humor as a Means of Estimating the Time of Death, Forensic Science International, Elsevier
Madea formula derivation: regression of vitreous K+ versus known PMI, formula PMI = 5.26 x [K+] minus 30.9, coefficient of variation
- cited in 1 question
Bharatiya Nagarik Suraksha Sanhita (BNSS) 2023, Government of India
Section 194 BNSS 2023 (corresponding to Section 174 CrPC 1973): inquest by police officer or executive magistrate on suspicious deaths
Open source - cited in 1 question
Madea, Burkhard and Henssge, Claus -- Timing of Death: The Body as a Clock, in Forensic Science International, Elsevier
Temperature plateau in early post-mortem cooling: sigmoid model and biological basis
- cited in 1 question
Madea, Burkhard -- Estimation of the Time of Death, in Forensic Science International, Elsevier
Limits of the Henssge nomogram: temperature equilibration, tropical climates, and transition to chemical PMI methods
How our mocks are built
Questions are written and edited by the ForensicSpot team and cited from peer-reviewed forensic textbooks, official syllabi and primary case law. Each one is verified before publishing. Detailed explanations show after you submit, so the test stays a real test. See a mistake? Tell us.
Common questions
What does the Forensic Medicine: PMI Estimation (Henssge, Newton, Vitreous K+) mock cover?+
This set drills the quantitative and semi-quantitative methods used to estimate post-mortem interval (PMI) in forensic medicine. Newton's Law of Cooling underpins algor mortis-based estimation: rectal temperature falls from 37 degrees Celsius toward ambient at a rate governed by body mass, clothing, and environmental conditions, and the Henssge nomogram (1988, Forensic Science International) converts rectal temperature, ambient temperature, and body weight into a 95%% confidence interval for PMI
How many questions and how long is the test?+
30 multiple-choice questions, 30 minutes total. Difficulty: medium. Tier: Premium.
Who is this mock for?+
Forensic science students and aspirants who want timed, exam-style practice with explanations and verified source citations on Forensic Medicine, NET. Useful for postgraduate entrance preparation and for BSc / MSc forensic students testing their recall under time.
Are the questions reviewed?+
Each question carries a verified source citation. Faculty review for individual questions is in progress.
Do I need an account to take this mock?+
Yes, a free ForensicSpot account is required to start a timed attempt — this lets you save progress, see per-question explanations after submission, and track your topic-level performance over time.