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What flies reveal about time of death at crime scenes

Did you know flies can help detectives determine time of death? Flies, especially blowflies, play a crucial role in solving crimes.

When a person dies, blowflies are often the first to the scene. If the environment is right, they’ll start colonising the body within minutes. 

Forensic Entomologist Gail Anderson for real-life examples of how flies have helped uncover cases on the Crime Insiders podcast:

Flies need certain conditions to attend a crime scene:
1️ Temperatures above 10°C 
2️ Dry weather
3️ Easy access to the body
4️ Daylight

This is where it gets interesting. Forensic entomologist Gail Anderson told the Crime Insiders podcast blowflies are extremely sensitive to light.

Blowflies are diurnal, meaning they shut down after sunset. Even if there are artificial lights, like streetlights, they’re tuned to natural cycles.

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If someone dies after sunset, flies won’t arrive until the next morning.

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Once flies arrive, they lay eggs in wounds or body openings. These eggs are visible to the naked eye, small clumps that can give investigators a timeline.

If no eggs or larvae are found when conditions were otherwise perfect, it suggests the death occurred when flies weren’t active – likely at night.

Investigators study flies and their behaviour to answer critical questions like when someone died, where they died, and what happened afterward.

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