How Long Does Rigor Mortis Last?

Rigor mortis is stiffening of the body after death due to muscle contractions. It is an important change that occurs after death, which can give details about the time of death. The time period rigor mortis takes to set in and the time period it takes to disappear gives crucial information about the time since death. Therefore, taking the rigor mortis time period correctly is important to get an accurate time of death.¹

Rigor mortis usually set in 2 hours after death, it takes roughly about 12 hours to completely establish in the whole body. Thenm it lasts for about 12 hours and starts to disappear in the same order it appeared. There is no fixed time on how long rigor mortis lasts, but studies show usually it can last for 18 hours to 2 days.²

After the disappearance of rigor mortis, the body enters in the secondary flaccidity which is also called autolysis. Autolysis is spontaneous self-destruction of tissues by the body enzymes present in the cells without any bacterial interferences. Once cells stop receiving nutrients and oxygen via blood circulation cells starts anaerobic breathing (without oxygen) by breaking adenosine tri-phosphate (ATP) into adenosine di-phosphate (ADP) to obtain energy. Anerobic respiration lasts for few hours, until all ATP reserves are exhausted. The anerobic respiration induces accumulation of lactic acid in cell tissues that disrupts cell function. Enzymes then collapse the cells and breaks them down.³

After full establishment of rigor mortis, the status last for about 12 hours and then it starts disappearing in the following order.

• 26 hours – first it disappears in papillary muscles (muscles in the eyes)
• 26 hours – lower jaw
• 28-30 hours – head, face and neck
• 28-30 hours – trunk
• 30-32 hours – large joints
• 32-34 hours – small joints
• 36 hours – rigor mortis is not present in the corpse⁴

The same factors that affected the onset of rigor mortis also influence the disappearance of rigor mortis too. These factors should be taken into account when the time of death is estimated.

• Condition Of The Body. Rigor mortis take a long time to set in and it lasts longer in well built, muscular and healthy people.
• Age Of The Deceased. Rigor mortis appears late and last longer in young and middle-aged healthy people.
• Cause Of Death. Rigor mortis only last for a short while following death due to tetanus, strychnine poisoning, death following violent activities and convulsions like epilepsy, electrocution, lightening; or death after many hours of violent exertion (in a battlefield) and death from cut throat and firearm injuries.
• Environment Factors. Rigor mortis lasts for a shorter period when bodies are exposed to warm and moist climates, whereas rigor mortis lasts for a longer time in cold environment.⁵

Rigor mortis is the stiffening of the of the body after death due to muscle contractions. The time period rigor mortis takes to set in and the time period it takes to disappear gives crucial information about the time since death. Therefore, taking the rigor mortis time period correctly is important to get an accurate time of death. Rigor mortis usually set in 2 hours after death, it takes roughly about 12 hours to completely establish in the whole body. Then it lasts for about 12 hours and starts to disappear in the same order it appeared. There is no fixed time on how long rigor mortis lasts, but studies show usually it can last for 18 hours to 2 days. The
condition of the body, age of the deceased, cause of death and environment factors influence the time rigor mortis lasts.

References: