[MUSIC] With fingerprinting, there's still a need for improved methods for visualization. Particularly for some of the surfaces where it's difficult to do. Another aspect of fingerprinting is the use of electronic databases. Fingerprint databases started over 100 years ago. But those were on the card and that required a fingerprint examiner to go through them one by one. Those databases are now electronic and computers can go through, finding matches. But we have to be careful. When an electronic database searches through fingerprints, it's not looking for perfect matches, it's looking for close matches. And a search of a database will give a number of close matches, a number of hits. The final judgment then comes from a human fingerprint examiner. And usually that is very reliable but, as with every human activity, it can go wrong. It went spectacularly wrong back in 2004 in the case of Brandon Mayfield Brandon Mayfield is an attorney in the state of Oregon in the USA. And he was detained as a material witness in the Madrid train bombings. So back in 2004, terrorists planted bombs on a number of commuter trains in the Spanish capital, Madrid. And when those bombs exploded, 191 people were killed. This was in the run up to the Spanish general election. And the bombs almost certainly influenced who became prime minister after that election. On a bomb fragment, a partial fingerprint was found. When that partial fingerprint was run through electronic databases, it was found to be a partial match to Brandon Mayfield. And this is why Mr. Mayfield was detained. However, there's an immediate problem with this idea, in that the bombs were planted in Spain and Mr. Mayfield lives in Oregon, which is an awfully long way away. And there was no actual evidence that Mr. Mayfield have traveled to Spain But, how did his fingerprint get on the bomb? And the answer is, it didn't. It was only a partial match, it wasn't a perfect match. The Spanish discovered that the fingerprint on the bomb was a perfect match to a man call Ouhnane Daoud. And he is their chief suspect in that case. So this case of Brandon Mayfield and the fingerprint reminds us of what Edmond Locard said, that physical evidence cannot be wrong, only human failure can diminish its value.