ASIS International (ASIS) Professional Certified Investigator Practice Exam

What is a sign of rigor mortis appearing in the body?

1. Decreased body temperature

2. Stiffness of the jaw

3. Blood settling under the skin

4. Skin discoloration

The correct answer is: Stiffness of the jaw

Rigor mortis is a postmortem change that is characterized by the stiffening of the muscles after death. The correct indication of rigor mortis appearing in the body is the stiffness of the jaw. This initial stiffness typically begins in smaller muscle groups, such as the eyelids and the jaw, before it progresses to larger muscle groups. As rigor mortis develops, it is a clear physiological sign that indicates the body is beginning to undergo the decomposition process. After death, the body experiences a drop in temperature, which is not a sign of rigor mortis, but rather a result of the cessation of metabolic processes. Blood settling under the skin leads to livor mortis, which is a different postmortem change. Skin discoloration can occur due to several factors, including livor mortis and decomposition, but it does not specifically indicate the onset of rigor mortis. Stiffness of the jaw is, therefore, the most direct sign associated with the appearance of rigor mortis in the body.