"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 Thursday'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.