How can insects play a new role in presenting forensic valuable evidence in court cases? Well, insects are found throughout nature, and those found at a crime scene can contribute to forensic investigations by examining human DNA found within the gastrointestinal tract. With the rapid and progressive advances in molecular biology techniques like Next Generation Sequencing (NGS), we can take insects from crime scenes and define the postmortem interval (PMI), which is the time elapsed since the discovery of the corpse by estimating either the developing larval stages of hematophagous insects (consume blood), or life cycle of all insects species in/on the corpse.
A case study published by Animal Behavior in 2017 examined the gastrointestinal tract of the Pendiculidae family, aka lice, to analyze human nuclear DNA to confirm the victim’s state of negligence prior to death. An elderly woman infested with lice passed away shortly after she was admitted to the emergency room. An autopsy and inspection of the women’s house was conducted to determine the cause of death, and the possibility of poor hygiene and family negligence. Numerous dead lice were found in her bedroom, and human DNA was extracted and analyzed from the lice gastrointestinal tract then compared to the blood taken from the autopsy as a reference. The combination of NGS technology and accurate stereomicroscopic inspection allowed the researchers to establish the best approach for obtaining a human DNA profile from head lice.
By applying the same methodology, human DNA from insects can provide powerful evidence in sexual assault cases where lice can transfer from attacker to victim (vice versa). Hematophagous insects, like lice, maintain indigestible human biological material as a source of DNA that can be used in investigations and should be seen as our allies.
Pilli, E., Agostino, A., Vergani, D., Salata, E., Ciuna, I., Berti, A., Lambiase, S. (2016). Human identification by lice: A Next Generation Sequencing challenge. Forensic Science International, 266. Retrieved October 05, 2017.
Alicia Bukowski
October 10, 2017 — 6:36 pm
This is honestly really cool! It seems like something out of Criminal Minds or SVU. I am curious as to how long to DNA stays intact in a tick? Does it expell it eventually? What’s the kind of time frame on using this data?
Brittany Simmons
October 11, 2017 — 6:18 pm
I just kept seeing the show Bones while reading this. Bad guys better watch out because even bugs can get them caught. I used to want to go into forensics and it’s just so exciting to see how the field continues to advance.
Nataly Ulloa
October 12, 2017 — 12:18 am
This is really cool! The intersection of lice and forensic science is something that I would have never expected to read. Hope that someday in the future we see this in a crime show.
Tiffany Guo
October 17, 2018 — 2:50 pm
I actually watch a lot of crime shows where different ways of detecting relations and causes are part of the story. However, I’ve never heard of using lice of identifying victims and the criminals. This must be send to the writers of crime shows!