7. The O. Brothers
During a jewelry heist at a Berlin department store in 2009, three masked men stole $6.5 million worth of merchandise but left behind a sweaty rubber glove. Police used traces of DNA from the sweat to find Hassan and Abbas O., 27-year-old twins whose full names by German law cannot be disclosed. The brothers, who have records for theft and fraud, came up in the German criminal database, but since they are identical twins and share 99.99% of their genetic information, there was no way for investigators to determine which sibling was linked to the snippets of DNA found at the crime scene. After five weeks of searching for further leads, police had no choice but to release the brothers. "From the evidence we have, we can deduce that at least one of the brothers took part in the crime," as authorities noted in a court ruling, "but it has not been possible to determine which one."