Science Questions

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

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.

December 2005