You know what - before we start reading about perfect crimes that failed literally at the last moment due to the slightest accident or because the criminals didn't take something into account, let's do one very important thing, as it seems to me: let's make a reservation.
'Perfect crimes' undoubtedly exist, but they aren't on this list. Do you know why? Because a truly perfect crime is one that neither we nor the police know about. Ideally, even the victim shouldn't know about the fact of the crime - if it was, let's say, a theft. Otherwise, it would be as perfect a crime as the Patriots' 2007 season was perfect. The same one with only one defeat. In the Super Bowl. Okay, now let's read on.
More info: Reddit