A police constable was found to be a paedophile a week after starting a new job which would have given him access to child abuse victims, a court heard.
Duncan was caught after a police operation in Surrey, the court heard
Iain Duncan, 28, from Bishopbriggs, East Dunbartonshire, was jailed after police found more than 3,000 child abuse images on his computers.
Duncan was a Strathclyde Police officer and had been seconded to the family protection unit just before his arrest.
The judge called for reports before sentencing in May.
Duncan resigned from the force after his arrest in January.
He admitted two charges of possessing images of child abuse at his own home and his parents' home and distributing them over a 28-month period between 2005 and 2008.
As well as finding the images on his two computers, police also discovered a six-minute video containing graphic images of babies being abused and prepared for abuse.
At the High Court in Glasgow, defence QC Paul McBride claimed the video was sent to the father-of-one's computer but never downloaded and viewed by him.
The film was so disturbing that the judge, Lord Turnbull, made a legal order banning newspapers from publishing the website so that others could not access it.
John Scullion, prosecuting, revealed that Duncan was caught after a police operation in Surrey which resulted in a paedophile being charged with possession and distribution of indecent images of children.
Subsequent investigations revealed e-mail addresses of fellow paedophiles with whom he had been exchanging the images - one of them was identified as Duncan.
Mr Scullion revealed that when charged, Duncan replied: "I know what I've done is wrong.
"I'm sorry. I'm ashamed."
The computers were analysed and almost 3,000 stills and three moving images were recovered from the one seized from his parents' house.
A total of 400 stills and moving images were discovered on his own laptop.
The court heard that experts are continuing to examine his computer.