Answer:
Once the heart stops beating, that means the blood in the body is no longer circulated, meaning that gravity starts to do its work. The blood starts to pool (liver mortis) at the bottom of wherever the body was positioned (which can help indicate if a body has been moved since they died in homicide cases etc.), and the body starts to turn that green-ish blue color, with a dark-purpley color forming at the bottom of wherever gravity takes it (for example, if the body died and remained in a position standing up, then the blood would pool at the feet, whereas if the body died and remained laying on its back, then the pooling would occur in the back area of the body). Additionally, rigor mortis (you can remember it as being rigid) occurs, which is when the body locks up, so the joints lock and are unable to move, which is why it is often hard to get rid of/pack up and throw away a body because over the span of several hours the body locks up (it eventually wears off). Lastly, we have algor mortis, which is the change in temperature of the cadaver. Since the blood is no longer circulating, the body has nothing to retain a constant temperature anymore. The body will begin to change the temperature accordingly based on the surrounding temperature (environments that are hotter than the body will heat it up and similarly to cooler environments). If the body is found before it reaches the local temperature, then the current temperature can be used to help estimate and determine the time of death (there is a formula for this, but I'll leave it up to you if you want to look into it). After a few days, the body will start to decompose, and it will inhabit insects, especially flies and such, and the stage of development of the larvae and/or fly can also help estimate and determine the time and date of death.
I hope this helps :) lmk if you need anything else