Between 1978 and 1983, Nilsen is known to have killed a minimum of twelve men and boys, and to have attempted to kill seven others (he initially confessed in 1983 to having killed about sixteen victims). Several hours later, he turned Stephen's head towards him, before kissing his body on the forehead and saying, "Goodnight, Stephen".

He died in 2018, entrusting the manuscript to his closest friend and it is now being published with the latter's permission. Though dealing with sensational and horrific matters he has managed, God knows how, to treat his material with such objectivity and restraint that what we have is not a penny dreadful from the Hammer House of Horror, but a bloody masterpiece'. With reference to his murders, Nilsen claimed that his emotional state upon the dates of the murders, in conjunction with the amount of alcohol he had consumed, were both core factors in his decision to kill. Another, unidentified victim had been so emaciated that he had simply been discarded under the floorboards. Austin’s “archive” included Nilsen’s autobiography, while the inmate was unsuccessfully trying to publish it.He also stated that, beginning in December 1978, he had killed "twelve or thirteen" men at his former address, 195 Melrose Avenue. Contrary to the prosecution claims, the defence counsel asserted that Nobbs' testimony reflected Nilsen's rational self being unable to control his impulses. All the bodies of the victims killed at Melrose Avenue were dismembered after several weeks or months of interment beneath the floorboards. Nilsen was initially posted to a Jobcentre in Denmark Street, where his primary role was to find employment for unskilled labourers. Upon leaving Nilsen's residence, Stewart had reported the attack to police, who in turn questioned Nilsen.

Nilsen attempted to dispose of the flesh, internal organs and smaller bones of all three victims killed at Cranley Gardens by flushing their dissected remains down his toilet. Nilsen grew to resent what he saw as the unfair amount of attention his mother, grandmother and later, stepfather displayed towards his older brother and younger sister. The families of Dennis Nilsen’s victims feel the killer is “laughing at them from beyond the grave”. In March 1982, Nilsen encountered 23-year-old John Howlett while drinking in a pub near Leicester Square.

In August, following a failed relationship, Nilsen came to the conclusion that his personal lifestyle was at odds with his job. Prior to leaving the property, Nilsen and fellow tenant Jim Allcock convened with Cattran to discuss the source of the substance. On one occasion, Nilsen discovered that, by using a free-standing mirror, he could create an effect whereby if positioning the mirror so his head was out of view, he could visualise himself engaged in a sexual act with another man.

No sexual activity had occurred, but this incident fuelled Nilsen's sexual fantasies, which initially involved his sexual partner—invariably a young, slender male—being completely passive. The following day, he refused to allow an acquaintance to enter his property, the reason being he had begun to dismember Sinclair's body on the floor of his kitchen. Initially, Nilsen experienced domestic contentment with Gallichan, but within a year of their moving to Melrose Avenue, the superficial relationship between the two men began to show signs of strain.To disguise the smell of the burning flesh of the six dissected bodies placed upon this pyre, Nilsen crowned the bonfire with an old car tyre. Austin and Nilsen soon became penpals and eventually met in person in 1992 when he was transferred to Whitemoor Prison in Cambridgeshire. During the summer and autumn of 1973, Nilsen began frequenting gay pubs and engaged in several casual liaisons with men.