How are DNA fingerprints made from samples left on clothing?

When you have DNA left on a piece of clothing, how do modern techniques match the DNA with the guilty suspect?

04 December 2005

Part of the show Forensics, DNA Fingerprinting and Human Origins

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Question

When you have DNA left on a piece of clothing, how do modern techniques match the DNA with the guilty suspect?

Answer

There is a national DNA database. When offenders are brought in, we take a sample of their DNA and it goes onto this database. Later, we try and match stains from a crime scene to people on that database. Obviously this assumes that the DNA is already on the database. This means that unless we have a suspect, there'll be no match.