"the corpse progresses through several forensically recognized stages of decomposition, including Fresh (before decomposition begins), Active Decay, which includes Bloating and Rupture, and Advanced Decay"

Creepy-spooky microbiology fact: Grave soil differs in biochemical composition from other soils. It's probably due to the action of microbial communities. Along the same rapidly-decomposing lines, forensic investigators may be able to use microbes to estimate a corpse's time of death in much the same way they may use insects.