What are the different methods used to determine the time of death in recent corpses?

The livor mortis is a phenomenon that occurs due to the settling of blood in the lower parts of the body after death.
The rigor mortis is a process of hardening of the striated, smooth and cardiac muscles due to post-mortem acidification and dehydration.
The chemical pupillary reactivity is the most useful phenomenon for calculating the time of death between the first two and four hours after death.
The study of gastric content can provide information about the nature, quantity, and state of digestion of the last meal, which can be used to estimate the time of death.