Ask Me Everything3

How does science catch criminals?

Criminals always take something away from a crime scene with them and leave something of their own behind. For example, they might unknowingly carry away fibers from a carpet and leave behind fingerprints. Crime Scene lnvestigators (CSIs) iook for these telltale pieces of evidence and scientists use them to link criminals with their crimes.

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Crime scientists can tell how long a body has been lying undiscovered by studying the creepy-crawlies living on it!

✓ Fingerprints l ✓ Shoe prints %    ✓ Tire prints

%    ✓ Hair

m ✓ Fibers

The number of hairs that fali out of a healthy scalp every day, so there’s a good chance that a criminal will drop a hair or two at a crime scene

240+

The number of prisoners freed in the U.S.A. as a result of DNA tests on evidence from past crimes

Ten things CSIs search for at a crime scene

✓    Documents

✓    Biood and other body fluids

✓ Ulegał drugs

1%/ Weapons ✓ Bullets

■ If DNA found at a crime scene is the same as DNA taken from a suspect, this proves that the suspect was at the crime scene.

■ Matching various samples of DNA like this is known as DNA profiling.

■ The chance of a wrong identification being madę from a good DNA profile is one in several billion.