Dean Dempster

A former Greater Manchester Police officer, Dean Dempster, has been sentenced to nine years in prison for child sex offences, including the sexual assault of a young girl while on duty. The case, uncovered by GMP's Professional Standards Directorate in collaboration with the Independent Office for Police Conduct, highlights a severe breach of trust by a public servant.

On 29 December 2023, Dempster, then aged 35 and from Manchester, was one of three officers responding to a domestic incident in Oldham involving an adult and children. While taking an account from a six-year-old girl away from his colleagues, Dempster sexually abused her, exploiting his position of authority meant to protect vulnerable individuals. The assault was reported that evening, leading to Dempster being confronted by his supervisor the following morning upon returning to duty. He was arrested the same day by officers in Oldham.

Further investigation revealed additional serious offences. A review of Dempster’s personal devices uncovered six counts of making indecent images of children, including two counts of the most serious category A material. Additionally, images on his mobile phone, taken from his body-worn video camera, included footage of a second clothed child from the December 2023 incident and another clothed child from a separate incident in 2022. Dempster pleaded guilty to these charges, as well as two counts of misconduct in public office for abusing his permissions as an officer and using policing footage for personal gratification.

Prior to his criminal sentencing, Dempster was sacked by the Chief Constable at an accelerated misconduct hearing in May 2024 and barred from policing. The court ordered him to serve five years on licence following his prison term and to sign the sex offenders’ register for life. GMP reviewed thousands of Dempster’s previous deployments and found no further evidence of criminal behaviour, though the force encouraged anyone affected to come forward.

Deputy Chief Constable Terry Woods commented on the case, stating: “I am angry and appalled at this abhorrent abuse of responsibility and trust. We commend the bravery of this young victim for coming forward. We apologise to her family and know nothing will ever undo the harm Dempster has caused to his victims.” Woods emphasised that Dempster represented a depraved exception with no prior indications of such behaviour in his vetting or record, and that GMP remains committed to child protection in Greater Manchester.

The victims' families have been kept informed throughout the investigation. This case was reported by Greater Manchester Police on 13 November 2024.