Abstract Estimating the postmortem interval (PMI) of human remains is important in criminal investigations. Microbes play an important role in the process of decomposition and can provide clues about the time elapsed since death. Host-associated and environmental microbial communities have been shown to undergo succession in a predictable, clock-like manner during decomposition. High-throughput DNA sequencing can be used to inexpensively and rapidly track these microbial community shifts, and machine learning techniques can use these data to develop predictive models. In this chapter, we discuss the development of a microbial clock for estimating PMI, as well as remaining knowledge gaps and hurdles to technology adoption.