Police say DNA evidence now ties Albert DeSalvo to the last of the Strangler murders

DA Dan Conley with Mary Sullivan's photo behind him.Updated with press-conference info.

Modern DNA techniques and dogged work by a detective who followed around a member of Albert DeSalvo's family last year have resulted in evidence that pretty conclusively ties DeSalvo to the last of the Boston Strangler murders in 1964, police and prosecutors announced today.

Still, just to be absolutely sure, prosecutors yesterday obtained a court order to exhume DeSalvo's body from a Peabody cemetery to optain samples with which to compare samples taken from the body and blanket of 19-year-old Mary Sullivan after her rape and murder in her Charles Street apartment, Suffolk County District Attorney Dan Conley said at a packed press conference this morning.

Conley said no similar DNA evidence exists for the remaining Strangler victims. DeSalvo's jailhouse confession was thrown out and he was convicted for another series of rapes.

Conley and Police Commissioner Ed Davis said earlier attempts at DNA analysis on the Sullivan samples in the early 2000s failed, but improvements in DNA technology meant police could attempt a new analysis last year. Conley said DNA from dried semen on Sullivan's body and blanket matched each other, proving they came from the same person. Next, they said, was proving a link to DeSalvo. They said that proved difficult because they were unable to find any testable samples from DeSalvo's files or his time in state prison until his 1973 murder.

So, Conley and Davis said, they turned to another route: The fact that men's Y chromosomes almost never change from one generation to the next. Last year, Davis said, a detective from the BPD fugitive squad began trailing one of DeSalvo's nephews, in the hopes he would touch something and then discard it in the trash - at which point the detective could retrieve it without asking for permission or a search warrant. Finally, Davis said, the detective watched the unnamed nephew drink from and discard a water bottle - which provided enough of a sample to show a match with the Y-chromasome data from the Sullivan samples.

Conley said investigators never simply asked the DeSalvo family for samples, in part because they were concerned it would produce unneccessary stress on the family - especially if it turned out the samples didn't match.

Casey Sherman, Sullivan's nephew, struggled with tears as he expressed gratitude for the police work after decades of an often lonely battle by his family to try to find out what really happened to Sullivan, who had moved into her Beacon Hill apartment just four days before her murder.

He added he realizes the answer won't be definitive until after DeSalvo's body is exhumed and samples tested.