Forensic Medicine Death and postmortem changes a47f743f All are true regarding muscular changes after death except - A Rigor mois occurs 1-2 hours after the death B Cadaveric spasm involves involuntary muscles C Rigor mois involves voluntary muscles D Rigor mois involves involuntary muscles High-Yield Explanation Cadaveric spasm involves a single group of voluntary muscles. Dr. Narayana Reddys Synopsis of Forensic Medicine & Toxicology 27 th edition pg. 81.