A film that a Skelmersdale paedophile was jailed for having in his possession has come under scrutiny from campaigning MP Tom Watson.
The “snuff” film, in which the victim is killed on camera, was seized during a raid on a Latvian man’s house in February last year.
The film shows a teenage girl begging a man not to hurt her before she is raped, then strangled with a wire causing her to foam at the mouth and her eyes to roll back into her head.
She is then wrapped in a plastic sheet and dragged from the room.
The police officer leading the inquiry was convinced she was murdered.
The judge who sentenced Andreas Bauminis, 22, to eight months in jail for possessing that film and other material in March also said she was probably killed.
From her accent, police believe the girl to be American, but despite having images of her and her apparent killer for 15 months, they have done nothing to help trace them.
Neither Britain’s Child Exploitation and Online Protection Centre (CEOP), which is part of the National Crime Agency (NCA), nor any US agency have yet been sent the video.
However, Lancashire Police have said they will send the video imminently.
Campaigning Labour MP Tom Watson said the revelations highlighted a serious failure in the UK’s policing of child pornography.
He is calling on the Government to establish a specialised independent agency similar to the successful Operation Predator in the US, which has arrested 8,000 paedophiles since it was launched in 2003.
Mr Watson said: “If the view of the judge and the police in this case is true, then Britain's police have sat on evidence of a child murder for over a year.
“It's negligent and scandalous the utmost urgency has not been applied with this case.
“The Americans should have been immediately informed and the NCA should have picked up the investigation."
“This case highlights the desperate inadequacies in our country's arrangements for investigating serious sexual abuse of children.”
Detective Constable Edward Wenham, who led the investigation, said it was the “worst thing I had seen by a country mile”.
He added: “My firm belief was this child was definitely killed.
“It was very difficult to sleep at night after seeing it. I have two children myself.”