Forensic Science What is the rule of 12 for rigor mortis? March 7, 2026 by pups | Leave a Comment The rule of 12 for rigor mortis is a general guideline stating that rigor mortis begins to set in about 12 hours after death, reaches its peak around 12 hours later, and then disappears approximately 12 hours after that. This means the entire process typically lasts about 36 hours. Understanding Rigor Mortis: The Rule of […] Read more »