Lividity

Lividity: With a Latin root meaning bluish, lividity can indicate anger (as in face red in anger) or a sickly pale (as in the blood drained from his face in fright), but when used technically in a medical or forensic context, lividity is the settling of the blood supply under the influence of gravity (after the heart has stopped pumping).

"So how is it possible that he could have fallen from the chair later?" says Tuchio.
"Lividity," says the witness. ...
"Then lividity as the blood settled ... might very easily cause the body to topple forward out of the chair.