The Boston Strangler case refers to the murders of thirteen women in the Boston area between June 1962 and January 1964, crimes that a handyman named Albert DeSalvo later confessed to but was never tried for. DeSalvo was killed in prison in 1973 while serving a life sentence for unrelated sexual assaults. In 2013, DNA testing confirmed he raped and murdered the final victim, 19-year-old Mary Sullivan, with the odds against a random match calculated at one in 220 billion.1National Institute of Justice. Solving Cold Cases with DNA: The Boston Strangler Case The other twelve murders have never been linked to him through physical evidence and remain officially unsolved.
The Murders
Between June 1962 and January 1964, thirteen women were killed in and around Boston. They ranged in age from 19 to 85, and most were single women living alone. The pattern shifted noticeably over the course of the spree. During the summer of 1962, the victims were older women, mostly in their sixties and seventies. By that winter, the killer began targeting younger women in their early twenties.
The method stayed consistent. There were no signs of forced entry, which led investigators to believe the victims had opened their doors willingly, possibly to someone posing as a maintenance worker or repairman. The women were sexually assaulted and strangled. The killer left the ligature, often the victim’s own nylon stockings, tied in a distinctive bow around the neck.
The press initially called the killer the “Phantom Fiend” before settling on the “Boston Strangler.” The final victim, Mary Sullivan, was found in her apartment on January 4, 1964. After her death, the killings stopped.
How Police Investigated at the Time
The murders triggered citywide panic. Residents bought new locks and carried tear gas. The crimes crossed multiple police jurisdictions within the Boston metropolitan area, and the agencies involved were not accustomed to coordinating investigations of this scale. Detectives in one district sometimes had no idea what evidence their counterparts in the next district had collected.
Massachusetts Attorney General Edward Brooke responded by creating a centralized task force known as the “Strangler Bureau,” staffed with detectives from multiple departments and overseen by Assistant Attorney General John S. Bottomly. Investigators still operated with severe limitations. DNA analysis was decades away from existence, and physical evidence collection was rudimentary by modern standards. Without forensic tools that could definitively link a suspect to a crime scene, detectives relied on witness statements, circumstantial evidence, and legwork.
How Albert DeSalvo Became the Suspect
DeSalvo was not initially a suspect in the Strangler murders. He came to police attention through a separate pattern of crimes. In his late twenties, he had earned the nickname “Measuring Man” for posing as a modeling agent to gain entry to women’s apartments, where he would take their measurements. After serving two years for those offenses, he escalated. By 1964, he was breaking into apartments wearing green work clothes, tying women up, and sexually assaulting them. Police dubbed this offender the “Green Man.”
On October 27, 1964, DeSalvo assaulted a young woman in her Cambridge apartment. She got a look at his face and gave police a description that matched the Measuring Man. DeSalvo was arrested on November 3 and released on bail. When authorities released his photograph, women in Connecticut identified him as their attacker in a separate series of assaults, and he was rearrested two days later.
The Confession and Why It Wasn’t Enough
The Strangler confession came unexpectedly. While DeSalvo was held at Bridgewater State Hospital for psychiatric evaluation, he told a fellow inmate, George Nassar, that he was the Boston Strangler. Nassar passed this along to his own attorney, F. Lee Bailey, who took DeSalvo on as a client. DeSalvo then provided hours of detailed, tape-recorded confessions to Bailey and investigators, describing crime scenes with specifics that had not been made public.
The confession had serious problems. DeSalvo’s nephew Casey Sherman later obtained the tapes and found them riddled with errors that suggested guesswork rather than firsthand knowledge. In the case of Mary Sullivan, DeSalvo claimed to have gagged and raped her, yet the autopsy found evidence of neither. Some investigators believed DeSalvo had been fed details by Nassar, who was himself a suspect in one of the killings. Others thought DeSalvo, a compulsive confessor with a history of exaggeration, simply absorbed crime scene details from news coverage and police questioning.
Prosecutors never charged DeSalvo with the Strangler murders. Without physical evidence corroborating his account, the confession alone could not sustain a murder prosecution. Instead, DeSalvo went to trial for the Green Man sexual assaults.
The Green Man Trial and DeSalvo’s Death in Prison
F. Lee Bailey pursued an unusual strategy. He introduced DeSalvo’s Strangler confession during the Green Man trial, not to prove DeSalvo committed those murders, but to argue that a man capable of such acts must be insane. The goal was a not-guilty verdict by reason of insanity. Massachusetts at the time applied a version of the M’Naghten rule, which required the defense to prove that the defendant could not distinguish right from wrong at the time of the crime, or that a mental disease rendered him incapable of controlling his actions.2Justia Case Law. Commonwealth v. McHoul The jury rejected the insanity defense. DeSalvo was convicted and sentenced to life in prison.
On the morning of November 26, 1973, DeSalvo was found dead in his cell at Walpole State Prison, stabbed multiple times. He had been working as an orderly in the prison hospital wing. Authorities questioned a suspect but never made an arrest. His murder remains unsolved.
How DNA Finally Tied DeSalvo to Mary Sullivan
The breakthrough came from a water bottle. In 2013, Boston police secretly followed one of DeSalvo’s nephews and collected a water bottle he had discarded. Forensic scientists extracted DNA from the bottle and compared it to seminal fluid that had been preserved from the Mary Sullivan crime scene since 1964.
The comparison used Y-STR analysis, which examines short tandem repeats on the Y chromosome. Because the Y chromosome passes from father to son with minimal change across generations, male relatives share nearly identical Y-STR profiles. That made it possible to test a living relative’s DNA against decades-old crime scene evidence without disturbing DeSalvo’s grave. The nephew’s sample produced a familial match to the Sullivan evidence.1National Institute of Justice. Solving Cold Cases with DNA: The Boston Strangler Case
The familial match was strong enough for a court order. On July 12, 2013, workers exhumed DeSalvo’s body from a cemetery in Peabody, Massachusetts. Scientists extracted DNA from a femur bone and three teeth, then ran a confirmatory test using standard autosomal STR analysis, which is far more precise because it examines DNA inherited from both parents and is unique to each individual.
On July 19, 2013, Suffolk County District Attorney Dan Conley announced the results. The DNA from DeSalvo’s remains matched the crime scene evidence with what Conley called an “unprecedented level of certainty.” Forensic specialists calculated the probability that a random white male other than DeSalvo left the biological evidence on Sullivan’s body at one in 220 billion.1National Institute of Justice. Solving Cold Cases with DNA: The Boston Strangler Case
The Twelve Cases That Are Still Open
The 2013 finding connected DeSalvo to one of the thirteen murders he confessed to. The other twelve cases have never been linked to him through physical evidence, and they remain officially unsolved. As recently as 2024, Boston police confirmed they are still actively investigating those killings and may have new information.
Because DeSalvo died in 1973, no criminal prosecution was ever possible. Under FBI guidelines, law enforcement can close a case through what is called “exceptional clearance” when they have identified the offender and gathered enough evidence to support an arrest but face a circumstance beyond their control that prevents prosecution, such as the suspect’s death.3FBI. Offenses Cleared The Sullivan case met those criteria. But exceptional clearance is an administrative classification, not a conviction. DeSalvo was never found guilty of any of the Strangler murders in a court of law.
The question of whether DeSalvo committed all thirteen killings, or just some of them, or was coached into confessing to crimes committed by someone else, may never be settled. Some investigators have long believed that more than one person was responsible, pointing to the shift in victim demographics midway through the spree and the inconsistencies in DeSalvo’s confessions. The DNA confirmed DeSalvo killed Sullivan. It did not confirm he killed anyone else.