Biomass loss during decomposition - A new tool in improving PMI estimation?

Area of Science:

• Forensic Science
• Decomposition Studies
• Taphonomy

Background:

• Estimating the minimum post-mortem interval (minPMI) is vital in forensic investigations.
• Concealment of remains can impede traditional minPMI estimation methods like temperature and insect activity.
• Understanding decomposition patterns with restricted insect access is crucial for accurate timeline determination.

Purpose of the Study:

• To investigate decomposition patterns and biomass loss in piglets with and without insect access.
• To assess the viability of using biomass loss as a method for estimating minPMI when insect colonization is prevented.

Main Methods:

• Utilized 48 stillborn piglets over a 14-day period across three years (2019-2022).
• Experimental groups included exposed controls and insect-excluded replicates using mechanical barriers allowing airflow.
• Daily observations recorded temperature, decomposition stage, weight, and insect activity, calculating accumulated degree hours (ADH).

Main Results:

• Insect exclusion barriers successfully prevented insect colonization but created a greenhouse effect, increasing ADH.
• The bloat phase was prolonged in insect-excluded piglets; they did not reach the dry phase by 2700 ADH, unlike controls.
• While insect exclusion reduced overall biomass loss compared to ADH, consistent trends in the rate of loss were observed, indicating other decomposition processes are active.

Conclusions:

• Biomass loss can occur in the absence of insect activity, driven by factors like bacterial decomposition.
• Biomass loss trends, even under insect exclusion, show potential as a reliable indicator for estimating minPMI.
• This research offers a novel approach to minPMI estimation, particularly valuable in cases of concealed remains.