Forensic Limnology: The Use of Freshwater Algal Community Ecology to Link Suspects to an Aquatic Crime Scene in Southern New England

During July, 1991, two young boys were brutally attacked by multiple teenaged assailants while fishing at a suburban Connecticut pond. After being accosted at knife point, the victims were bound with duct tape, beaten with a baseball bat and dragged into the pond to drown. One victim managed to free himself, rescue his colleague, and summon help from local residents. An exhaustive investigation led to the rapid apprehension of three suspects. In an effort to link the suspects to the crime scene, sediment encrusted sneakers were seized from both assailants and victims, and analyzed for aquatic microorganisms. Numerous species of diatoms and scaled chrysophytes (planktonic algae) were recovered from the sneakers and from reference samples of pond sediment. The marked similarities in the algal communities present on the sneakers indicated exposure to a common freshwater habitat, most probably the crime scene pond. Additional analyses revealed that Mallomonas caudata was the dominant scaled chrysophyte species in each sample, and that there was no significant difference in the ratios of three species of the diatom Eunotia between all samples examined. These findings further supported the idea that all of the samples originated from a common, if not the same, locality. This case further exemplifies the applicability of aquatic community ecology to forensic investigations.