According to court records, Dennis Ferguson’s pre-1987 criminal history contains “many convictions for false pretences, various assaults on children and indecent assaults on females”, including five convictions for child molestation. In 1987 Ferguson was imprisoned in Long Bay Jail after being convicted on multiple fraud charges. After being released from Long Bay Jail in July 1987, Ferguson, then aged 39, and his 23-year-old male lover, Alexandria George Brookes, abducted three children, two boys and a girl, from Sydney aged six, seven and eight. Ferguson had previously got to know the children’s father, who was a fellow inmate in Long Bay Jail, and Ferguson was told that the children had previously been sexually abused. Ferguson and Brookes flew the children to Brisbane, and sexually assaulted them in a house in the Brisbane suburb of Kedron. The following night, Ferguson and Brookes moved the three children to a motel in the suburb of Ascot, where they again abused the children. Police arrested Ferguson and Brookes at the motel, where they found Ferguson naked with the children. Ferguson told police, “I can help you. Pornography. Kiddy porn, I can get you kiddy porn.” Dennis Ferguson claimed he was innocent, accusing one of the boys he molested of committing the crimes, but a jury found him guilty of all counts of abduction and assault of the three children. He was sentenced to 14 years’ imprisonment, by a judge who noted there was no chance he would be rehabilitated.

While in jail Dennis Ferguson refused to take part in rehabilitation programs, and attempted to obtain police photographs of his victims under the Freedom of Information Act. An order was obtained requiring Ferguson to report his whereabouts to police after fellow inmates reported plans by him to molest the eight-year-old daughter of the family with whom he would reside after being released. In 2003, New South Wales Police surveillance located Ferguson at Parramatta Public School. Ferguson was forbidden from entering schools and claimed he was trying to distribute cleaning products for groups needing to raise funds. A court convicted him under the NSW Child Protection Offenders Registration Act, and he was sentenced to a further 15 months’ prison in the John Morony Correctional Centre. He was released in December 2004. The following year, in November 2005, Ferguson was charged with sexually assaulting a 5-year-old girl at her home in the Queensland town of Dalby. In a rare legal move, the judge granted Ferguson a bench trial (without a jury), as he considered Ferguson would not receive a fair trial by jury, due to the enormous amount of media coverage. The judge found that while the girl had been molested when Ferguson, convicted child sexual abuser Allan Guy and another man had been at her house, it could not be proven that Ferguson had been responsible for the abuse.

On 30 December 2012, Dennis Ferguson was found dead in his Surry Hills Flat in inner-Sydney. He had been dead for several days before his body was found. On 6 January 2013, News Limited reported that Ferguson deliberately ended his life by discontinuing his diabetes medication. However, friends said that Ferguson left no suicide note and was feeling confident about his upcoming court case, after being caught trying to sign up to do volunteer work with children in Bondi Junction in October and November. It also reported that shortly before his death, he had told supporters that police were making his life a “living hell”. Ferguson’s advocate, the Justice Action campaigner Brett Collins, said that the police continuously “undermined” Ferguson’s efforts to redeem himself and claimed that the police had informed the media about his whereabouts at least twice.