This topic is heavily debated on how long it actually is but by your question I'm assuming that would be true. I've seen some things that have said 2 1/2 - 3 hours but others have said 4 and above.
Though digestion varies from person to person, a meal is typically fully digested (and the stomach empty) six hours after eating. To determine time of death, examiners commonly look at body temperature and rigor mortis (for more recently killed victims) or decomposition and insect activity (for bodies found later).
