The
murderer absconds with a smirk, knowing he has covered his tracks like a pro —
no witnesses, no fingerprints or footprints, no stray hairs to betray his
identity.
But if a mosquito
bit our cocky assassin at the crime scene, it could one day lead to a
conviction, according to study published Monday in the journal PLOS ONE.
That is because
researchers at Nagoya University have shown that human blood extracted from a
buzzing bloodsucker can be traced back to its original owner up to 48 hours
after a skeeter has siphoned it off.
“This technique can
help police work out who was at a crime scene,” lead scientist Toshimichi
Yamamoto said in a statement. “In the future, it might provide evidence that
can be used to convict offenders.”
No one knew how long
human blood drawn by a mosquito kept an identifiable DNA profile, so Yamamoto
and a team of forensic scientists decided to find out.
They recovered blood
from mosquitoes who had bitten volunteers, and then used a technique called
polymerase chain reaction (PCR) to examine it.
PCR is a standard
tool in forensics for amplifying a tiny DNA fragment up to thousands of times.
The researchers
found that they could accurately match the minuscule blood traces to the
volunteers who had offered themselves up as a meal, even after two days of
digestion in a mosquito’s stomach.
After three days,
however, the blood completely broke down.
The experiments were
performed with two species, Culex pipiens pallens and Aedes albopictus, both
found throughout much of the tropical and subtropical world.
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