DeSalvo admitted to the murders, which took place between 1962 and 1964, but police lacked the evidence to bring the factory worker to trial. Instead, he was tried in series of unrelated assaults, convicted and sentenced to life in prison. He was stabbed to death in his cell in 1973.
The DNA probe began last summer, when scientists in the police department's Cold Case Squad began looking at 14 boxes of evidence from two of the strangler's victims, said Kevin Jones, a police spokesman. Those tests were inconclusive.
Capt. Timothy Murray told The Boston Globe: Â"The Strangler case is one of the most notorious in the country. If we can solve this, it might spark other cities to use DNA to solve old crimes. There's no statute of limitations on murder.Â"
Many of the lead investigators, as well as the chief pathologist who performed the victim autopsies, are dead.
Several other obstacles stand in investigators' way. Police know evidence exists - case logs describe sperm samples swabbed from some of the victims - but have been unable to locate the items. And they think the knife used to kill DeSalvo was preserved, but they haven't been able to find it either.
The knife could provide a clean DNA sample, so investigators wouldn't have to exhume DeSalvo's body. But police said they are willing to dig up the body if they find DNA samples that need to be matched.
No physical evidence tied DeSalvo to the crimes. A 1995 book by Susan Kelly claimed that DeSalvo could have learned all the details about the killings information with which he impressed investigators by reading the newspapers. Kelly also said DeSalvo could have learned the information from the real killer in prison.
Attorney F. Lee Bailey, who defended DeSalvo, said he believes his client committed the murders, and was insane at the time. DNA tests should confirm DeSalvo's guilt, he said in a telephone interview from Florida.
If they don't, Â"you've got a real news story, because every cop and the attorney general bought into his story,Â" Bailey said.
Casey Sherman, a Rockland man whose aunt, Mary Sullivan, was killed by the Strangler in 1964 when she was 19, said: Â"Our family believes Albert DeSalvo was not the Boston Strangler.Â"
Â"I've spoken with the DeSalvo family themselves, and what they say is Albert told them he wasn't the Strangler,Â" Sherman said, adding he believes there were several killers.
Some psychiatrists have noted that serial killers typically choose victims with similar characteristics, but the Boston victims ranged from Sherman's 19-year-old aunt to several elderly women.
The Strangler often tied bows around the necks of his victims, as if tey were wrapped presents.