A police officer who assaulted a vulnerable young woman while on duty and superimposed his face on child abuse footage has been jailed for nine years.

Dean Dempster, 35, who was a responding officer with Greater Manchester Police (GMP) based in Oldham at the time, sexually touched the child while responding to a disturbance in Oldham on December 29, 2023.

He was arrested the next day at work following a discussion about a formal complaint against him, and his personal and work phones were confiscated.

It later became apparent that prior to his arrest that morning, Dempster had deleted some material and applications from his personal mobile phone.

His home was searched and a number of items were recovered, including another iPhone, a pack of four folded pairs of children’s underwear, shredded underwear in a bag, a picture disc and two hard drives .

Dempster’s mobile phone and iPad were found to contain 104 indecent images of children classified at category A – the most serious – including 30 pseudo images at that level, as well as 440 category B images, including 129 pseudo images and 2,472 category C images, including 39 pseudo images.

A large number of pseudo-images had been superimposed to show Dempster with children.

Examination of his devices suggested that Dempster downloaded indecent images of children from December 15, 2021 to December 29, 2023.

Further analysis of internet usage revealed that Dempster searched for children’s feet and websites were accessed in December 2023 that contained content involving children’s feet.

Dempster was dismissed by GMP following an expedited misconduct hearing in May 2024.

He previously pleaded guilty to one count of sexually assaulting a child under 13, six counts of making indecent images of children and two counts of misconduct in public office.

The prosecution followed an investigation by GMP’s Professional Standards Directorate, led by the Independent Police Conduct Office.

At Liverpool Crown Court today, Dempster was jailed for nine years.

Malcolm McHaffie, Head of the Special Crime Branch of the Crown Prosecution Service, said: “Dean Dempster’s actions were disgusting and betrayed the trust placed in him as a serving police officer.

“The sexual assault took place while on duty and there is no doubt that the victim was deeply affected by being targeted by someone in authority.

“Subsequent searches of Dempster’s devices and his home address revealed further deplorable offenses and he is now facing the consequences of his actions.

“The Crown Prosecution Service will not hesitate to bring charges against those who abuse their position and target young people in such a reprehensible way.”