Why does a body twitch after death?

After death, a body may twitch due to a process called cadaveric spasm or postmortem muscle contractions. These involuntary movements occur as a result of biochemical changes in the muscles and nervous system. The depletion of ATP (adenosine triphosphate) and the release of calcium ions can cause muscle fibers to contract briefly. This phenomenon can happen shortly after death, often giving the appearance of movement even though the body is unresponsive.