Wiping the gun clean has long been considered best practice for villains but may soon become a quaint custom that will ultimately prove fruitless. Researchers have developed a method to ‘visualize fingerprints’ even after the print itself has been removed by measuring the corrosion of the surface by deposits from the fingerprints. The technique can enhance – after firing– a fingerprint that has been deposited on a small caliberhttp://en.wikipedia.org/wiki/Caliber metal cartridge case before it is fired. The technique promises the ability to reopen many cases and solve cold cases around the world because the “underlying print never disappears” according to...