The city was panic stricken and the situation prompted the drafting in of a top investigator to head the hunt for the Strangler. Massachusetts Attorney General Edward Brooke, the highest-ranking law enforcement officer in the state, began work on January 17, 1964, to bring the serial killer to book. There was pressure was on Brooke, the only African American attorney general in the country, to succeed where others had failed.

Brooke headed up a task force that included assigning permanent staff to the Boston Strangler case. He brought in Assistant Attorney General John Bottomly, who had a reputation for being unconventional.

Bottomly’s force had to sift through thousands of pages of material from different police forces. Police profiling was relatively new in the early 1960s, but they came up with what they thought was the most likely description of the killer. He was believed to be around thirty, neat and orderly, worked with his hands and was most likely a loner who may be divorced or separated.

In fact, the killer ended up being found by chance, not by the work of the police force.

After a spell in prison for breaking and entering, DeSalvo went on to commit more serious crimes. He had broken into a woman’s apartment, tied her up on the bed and held a knife to her throat before molesting her and running away. The victim gave the police a good description, one that matched his likeness sketch from his previous crimes. Shortly afterward, DeSalvo was arrested.

It was after he had been picked out of an identity parade that DeSalvo admitted to robbing hundreds of apartments and carrying out a couple of rapes. He then confessed to being the Boston Strangler.

Despite the police not believing him at the time, DeSalvo was sent to Bridgewater State Hospital to be assessed by psychiatrists. He was assigned an attorney by the name of F. Lee Bailey. When DeSalvo’s wife was told by Bailey that her husband had confessed to being the Strangler she couldn’t believe it and suggested he was doing it purely for payment from the newspapers.

During his spell in Bridgewater, DeSalvo struck up a friendship with another inmate, an intelligent but highly dangerous killer called George Nassar. The two apparently had worked out a deal to split reward money that would go to anyone who supplied information to the identity of the Strangler. DeSalvo had accepted that he would be in prison for the rest of his life and wanted his family to be financially secure.

Bailey interviewed DeSalvo to discover if he really was the notorious killer. The attorney was shocked to hear DeSalvo describe the murders in incredible detail, right down to the furniture in the apartments of his victims.

DeSalvo had it all worked out. He believed he could convince the psychiatric board that he was insane and then remain in prison for the rest of his life. Bailey could then write up his story and make much needed money to support his family. In his book The Defense Never Rests, Bailey explains how it was that DeSalvo managed to avoid detection. DeSalvo was Dr. Jekyll; the police were looking for Mr. Hyde.

After a second visit and listening to DeSalvo describe in grisly detail the murder of 75-year-old Ida Irga, Bailey was convinced his client was the Boston Strangler. When he asked DeSalvo why he chose a victim of such an age, the man coolly replied that “attractiveness had nothing to do with it.”

After many hours of questioning and going into minute detail of what the victims wore or how their apartments looked, both Bailey and the police were convinced that they had the killer. One disturbing revelation was when DeSalvo described an aborted attack on a Danish girl. As he was strangling her he caught sight of himself in the mirror. Horrified by the ghastly vision of what he was doing he released her and begged her not to tell the police before fleeing.

DeSalvo was incarcerated in what is now known as the MCI-Cedar Junction prison in Massachusetts. In November 1973, he got word to his doctor that he needed to see him urgently; DeSalvo had something important to say about the Boston Strangler murders. The night before they were to meet, however, DeSalvo was stabbed to death in prison.

Because of the level of security in the prison, it is assumed that the killing had been planned with a degree of co-operation between employees and prisoners. Whatever the case, and though there were no more murders by the Strangler after DeSalvo had been arrested, the Strangler case was never closed.