BOSTON » The man who once claimed to be the Boston Strangler has been linked to one of the 11 victims by DNA evidence for the first time, leading authorities to plan to exhume his remains for further testing and perhaps putting to rest speculation that Albert De Salvo may not have been the notorious killer after all.

DeSalvo’s remains will be exhumed after authorities concluded that DNA from the scene of Mary Sullivan’s rape and murder produced a "familial match" with him, Suffolk District Attorney Daniel Conley said today. Conley said he expected investigators to find an exact match when the evidence is compared with his DNA.

Sullivan, 19, was found strangled in her Boston apartment in January 1964. Sullivan, who had moved from her Cape Cod home to Boston just days before her death, had long been considered the strangler’s last victim.

The announcement represented the most definitive evidence yet linking DeSalvo to the case. Eleven Boston-area women between the ages of 19 and 85 were sexually assaulted and killed between 1962 and 1964, crimes that terrorized the region and grabbed national headlines.

DeSalvo, a blue-collar worker and Army veteran who was married with children, confessed to the 11 Boston Strangler murders, as well as two others. But he was never convicted of the Boston Strangler killings.

He had been sentenced to life in prison for a series of armed robberies and sexual assaults and was stabbed to death in the state’s maximum security prison in Walpole in 1973 — but not before he recanted his confession.

An attorney for DeSalvo’s family said today they believe there’s still reasonable doubt he killed the Strangler’s last supposed victim, even if additional DNA tests show a 100 percent match.

DeSalvo family lawyer Elaine Sharp said previous private forensic testing of Sullivan’s remains showed other male DNA was present that didn’t match DeSalvo.

Authorities countered by saying their evidence was preserved in a lab, while the evidence used in private testing was very questionable.

Sharp said the family is also outraged that police secretly followed one of DeSalvo’s relatives to collect DNA evidence from a discarded water bottle to use in their testing.

A nephew of Sullivan’s who for years maintained that DeSalvo did not kill his aunt and even wrote a book on the case pointing to other possible suspects acknowledged the new findings point to the man he’d defended.

Casey Sherman said he accepted the new findings after concluding that the DNA evidence against DeSalvo appeared to be overwhelming.

"I only go where the evidence leads," he said, thanking police and praising them "for their incredible persistence."

Casey Sherman also expressed sympathy for the DeSalvo family, whom he had aligned with in the past in a shared belief that DeSalvo didn’t kill his aunt.

That belief was based on DeSalvo’s taped confession to Sullivan’s killing, which Sherman said in 2000 was inconsistent with other evidence in the case.

The families of DeSalvo and Sullivan jointly sued the state for release of evidence while pursuing their own investigation. Sullivan’s body was exhumed in 1999 for private DNA testing as part of the effort.

Attorney F. Lee Bailey, who helped to obtain the confession from DeSalvo, said today’s announcement will probably help put to rest speculation over the Boston Strangler’s identity.

Bailey had been representing another inmate who informed the attorney that DeSalvo knew details of the crimes. Bailey went to police with the information, and he said DeSalvo, who was already in prison for other crimes, demonstrated he knew details only the killer would know.

Bailey would later represent DeSalvo.

"It was a very challenging case," said Bailey, who lives in Yarmouth, Maine. "My thought was if we can get through the legal thicket and get this guy examined by a team of the best specialists in the country, we might learn something about serial killers so we could spot them before others get killed."

Officials stressed that the DNA evidence links DeSalvo only to Sullivan’s killing and that no DNA evidence is believed to exist for the other Boston Strangler slayings.

State Attorney General Martha Coakley, however, said investigators hoped that solving Sullivan’s case might put to rest doubts about DeSalvo’s guilt.

Conley said the "familial match" excludes 99.99 percent of suspects but isn’t enough to close the case.

Associated Press writers David Sharp in Portland, Maine, and Mark Pratt in Boston contributed to this report.