Albert Henry DeSalvo was born on September 3, 1931, in Chelsea, Massachusetts. His father, Frank DeSalvo, was a sadistic, violent, alcoholic fisherman from Newfoundland who brutally abused his wife, Charlotte DeSalvo, Albert and his five siblings, one brother and four sisters, and would regularly take home prostitutes and have sex with them in front of his family. Albert once saw him beat all of the teeth out of Charlotte's mouth and then break her fingers one by one. Frank also once sold all his children to a farmer in Maine for $9, though they managed to break out and return home, at which point Frank began teaching him to steal and encouraged him to do so. In 1943, aged 12, Albert was arrested for battery and robbery and was sent to a reform school. The next year he was paroled and got a job as a delivery boy. He was sent back to the same reform school for auto theft only two years later.

At the age of 17, after being released, he enlisted in the U.S. Army and was sent to Europe, where he met a German woman, Irmgard Beck, whom he married and brought back to the States, where he did a second tour in the Army. During his second tour, at Fort Dix, New Jersey, he was arrested for molesting a nine-year-old girl, narrowly escaping conviction because her parents wouldn't press charges. In spite of his court-martial, he was honorably discharged in 1956. Shortly afterward, he was arrested twice for robbery. He demanded sex from his wife six times a day and called her rigid if she refused. When their first child, a girl named Judy, was born with a pelvis disease, she kept their sex life to a minimum, afraid that any other children they might have might also have conditions. They eventually conceived a healthy son, Michael, together. In the time between DeSalvo's second discharge and March of 1960, he committed a series of attacks known as the Measuring Man crimes, during which he would pose as a talent scout from a modeling agency named "Johnson" in order to get inside women's homes and con them into undressing so he could pretend to take their measurements, fondling them while doing so. Though he confessed to the attacks when he was arrested for burglary, no charges for them were filed and he was sentenced to 11 months in prison for only the burglary charge.

After being released from prison, DeSalvo committed a series of home invasions known as the Green Man attacks. Dressed in green work-clothes, he would break into apartments belonging to women, tie them to their beds in a spread-eagle position at knifepoint, sexually assault them, and leave. A victim who was attacked on October 27, 1964, gave the police a description of the assailant, which led the investigators to DeSalvo and was published in newspapers, leading to more victims coming forward. Earlier on October 27, DeSalvo attempted to break into a home by posing as a motorist. In November, he was arrested for the assaults and confessed not only to them but also to being the Boston Strangler.