Insects shape the cadaver decomposition microbiome and postmortem interval estimation accuracy

Area of Science:

• Forensic Science
• Microbial Ecology
• Decomposition Biology

Background:

• Carrion decomposition relies on insects and microbes, forming specialized networks.
• Microbiome-based models show promise for estimating postmortem interval (PMI).
• The impact of indoor environments on cadaver microbiome assembly is unknown.

Purpose of the Study:

• To investigate how enclosed shelter affects microbial community assembly during human decomposition.
• To assess the impact on postmortem interval (PMI) modeling.
• To understand the role of insects in dispersing decomposer microbes.

Main Methods:

• Comparison of microbial communities in indoor versus outdoor human cadaver decomposition.
• Analysis of microbial community assembly and successional patterns.
• Development and testing of machine learning models for PMI prediction using microbial data.

Main Results:

• Indoor cadavers showed delayed colonization by key decomposer microbes due to restricted insect access.
• Machine learning models trained on outdoor data underestimated PMI for indoor cadavers.
• Delayed blow fly maggot colonization correlated with increased PMI prediction errors.

Conclusions:

• Insects are crucial for dispersing microbes that drive decomposition and influence PMI predictions.
• Incorporating indoor microbial data and insect activity significantly improves PMI model accuracy.
• Microbiome-based forensic tools show feasibility across diverse decomposition environments.