Why flies can muck up a crime scene

Something New Every Day – Lecture 18 – Blood patterns

Flies might excite entymologists in the crime lab but they can seriously muck up the work of the serology team. Flies in a crime-scene can ingest blood and regurgitate it, which alters the composition and nature of the blood and thus the evidence.

They also excrete the blood in tiny amounts that, if there are enough flies, can replicate a kind of blood spatter and misdirect crime scene analysts.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series