Former police officer jailed after child sex offences uncovered by GMP unit for professional standards

A former police officer who was sacked earlier this year for sexually assaulting a child on duty has now been jailed for nine years.

Dean Dempster (aged 35), from Manchester, has also been ordered to sign the sex offenders’ register for life after previously admitting to sexually assaulting a child while on duty working as a response officer in Oldham.

He was convicted and sacked by the Chief Constable at an accelerated misconduct hearing earlier this year. He has since admitted six counts of making indecent images, and two counts of misconduct in public office.

On 29 December 2023 Dempster was one of three officers responding to a domestic incident involving an adult and children. It was while taking an account from a six-year-old girl, away from colleagues, that he sexually abused her when he should have been there to protect her.

After we investigated a complaint received later that evening, Dempster was immediately confronted by his supervisor when he returned to duty the next morning. 

He was arrested that day by officers in Oldham and relentlessly pursued by our Professional Standards Directorate to explore any further evidence of offending, in an investigation directed by the Independent Office for Police Conduct.

A review of Dempster’s devices revealed further serious offending to include making of indecent images of children, to which he pleaded guilty to six counts of including two counts of the most serious category A.

Our investigation also found images on his mobile phone taken from his body-worn video camera at the incident in December 2023 of a second clothed child, and of another clothed child at a separate incident dating back to 2022. The victims of both families have been made aware and kept updated throughout our investigation.

Dempster pleaded guilty to two counts of Misconduct in a Public Office for abusing the permission granted to him as a police officer and for using footage, captured for a policing purpose, to possess for his own perverse gratification.

We have reviewed thousands of Dempster’s previous deployments while at the force and did not find any further evidence of criminal behaviour. However, anyone who is affected by this case is encouraged to contact police and they will be listened to.

We sacked Dempster at the earliest legal opportunity in May 2024 and he has been barred from policing. He has been ordered to serve five years on license following his prison sentence.

Deputy Chief Constable Terry Woods said: “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.

“Dempster represents the very worst of society. He is not a police officer; he is a child sex offender, a criminal, and he has no right to be near police uniform or serve the public. Dempster was rightfully arrested and charged before he could ever work in our communities again.

“We have thoroughly reviewed Dempster’s vetting and can confidently say there was nothing to remotely suggest he had a sexual interest in children. He was a man with a career in public service and his record showed no signs of warning.

“Dempster is a depraved exception who we have wasted no time in dismissing and disowning.

“The thousands of officers he has let down are committed to the protection of children in Oldham and Greater Manchester, and anyone who undermines this priority has no place in GMP.”