When does lividity typically become fixed?

Lividity, or postmortem hypostasis, refers to the pooling of blood in the lower parts of a body after death due to gravity. Normally, lividity begins to develop within a few hours after death, appearing as a purplish discoloration on the skin. The process of fixing, where the discoloration becomes permanent, typically occurs around 8 hours after death.

At this point, the red blood cells break down, and the pooling of blood is no longer reversible. Understanding the timing of lividity is crucial for forensic investigations, as it can help establish a time frame for death, which may provide significant context during a criminal investigation. In contrast, earlier time frames (like 2 and 4 hours) do not accurately reflect the point at which lividity becomes a reliable indicator of death, and the 24-hour mark exceeds the typical window for this physiological change.