Being an identical twin might seem like a great way to fool a DNA test and get away with the perfect crime. But furry forensic experts can make sure justice is served. In a new study, researchers instructed a group of children, including two sets of identical twins and two sets of fraternal twins, to swab the insides of their cheeks and place the swabs in glass jars. Working with ten police German shepherds and their handlers from the Czech Republic police, the researchers then ran a mock crime scene investigation. The handler presented one twin’s scent to the dog and then told it to go find the matching scent in a lineup of seven jars, which included the other twin’s scent. In twelve trials per dog, none of them ever identified the wrong twin as a match, the researchers report online this week in PLoS ONE, even though the children lived in the same home, ate the same food, and had identical DNA. No word yet on whether these dogs will be getting their own CSI spinoff.