Effect of arson fires on survivability of entomological evidence on carcasses inside vehicle trunks

Three vehicles with trunks containing pig (Sus scrofa domesticus Erxleben) carcasses which had been allowed to decompose for 30 days, were set alight in controlled burns to determine whether forensically valuable insect evidence could still be recovered. Each car trunk contained the remains of a carcass, together with its associated carrion insect fauna. An insect collection was performed prior to the fires. Each car was then set alight using a small amount of gasoline as an accelerant, poured onto the driver's seat, lit by a burning stick. The fire was allowed to reach its peak before being extinguished. In all cases, the fires completely destroyed the vehicles. The vehicles were examined the following day and insect evidence was collected. In all cases, large amounts of burned, charred and undamaged insect evidence remained, including identifiable prepuparial 3^rd instar larvae, live pupae inside intact puparia and empty puparial cases. As well bones and unburned clothing were also intact. One car did not burn as well as the others with the fire not involving the trunk area as much as in the other cars. Once the fire was extinguished, it was clear that the reason for this was the presence of a steel fire wall, between the passenger compartment and the trunk. This reduced the spread of the fire to the trunk and increased evidence survival. However, in all vehicles, insect evidence survived, which could still be used to estimate the period of insect colonization and thereby infer the minimum elapsed time since death. The evidence was also a clear indicator that the decedent had not died in the fire. After the fire, the carcass remains were still attractive to blow fly adults (Diptera: Calliphoridae). In car fire cases it is important to consider that entomological evidence may still be just as useful in the investigation as in non-burned cases.