Nearly five decades after the last Boston Strangler murder went unsolved, police say they can now prove who the murderer was, even though the prime suspect has been dead for 40 years. The case of one of the nation's most notorious serial killers dates back to 1962 when the first of 11 women were murdered in the Boston area. Nearly all the victims were sexually assaulted and then strangled with their own stockings, with the last killing taking place in 1964.

Later in 1964, a man named Albert DeSalvo was arrested on an unrelated sexual assault charge and he confessed to the killing. However, there was no physical evidence tying him to any of the crimes and the confession was ruled inadmissible in court. He was sentenced to life in prison on the other crimes, but the Boston Strangler crimes remained officially unsolved.

DeSlavo was murdered in prison in 1973, but that did not end the fascination with the case or the determination to solve it. Now police say they have the physical proof they've been looking for all along —  thanks, of course, to modern DNA technology. Police announced on Thursday that they are "in a position" to charge DeSalvo with the murder of Mary Sullivan, who was the final victim in 1964.

Sullivan's case is the only one where any DNA evidence remains, and police said at a press conference today those samples were recently re-tested, using more advanced technology that was able to separate Sullivan's DNA from the perpetrator's. Police then surreptitiously obtained a DNA sample from a nephew of DeSalvo (they followed him around and then picked up a discarded water bottle) and initial tests suggested a match. That led to a warrant to exhume DeSalvo's body next week for a more definitive conclusion.

Even if DeSalvo is tied to Mary Sullivan's murder, there will still be doubts (as there have been for many years) that he is the Boston Strangler, or that just one person was responsible for all the crimes. There were errors in his confession as well a different method of killing in some of the deaths. Just 12 years ago, a different investigation claimed that DNA proved that DeSalvo was innocent. But for some of the victim's families and the investigators fighting to solve the crime, this new break may be enough to give them the peace of mind they've been searching for.