This is the moment when a cold-hearted sectarian killer was trapped by his own efforts to cover up his cowardly crime.

William Hill (24) bludgeoned innocent David Cupples to death in a fit of rage, thinking that the Protestant Army cook was a Catholic.

After having a row with his ex-girlfriend, Hill bumped into his victim near a filling station in north Belfast and carried out a savage and unprovoked attack at around 7am on Sunday, December 22 2002.

As Mr Cupples lay fighting for his life Hill was busy trying to cover his tracks.

He went to an all-night filling station four hours AFTER the murder to remove CCTV footage that he feared would place him at the murder scene.

But his attempts to remove all traces connecting him to the brutal killing actually trapped Hill as he fled the filling station empty-handed — but AFTER giving cops enough evidence to nail him and two pals who tried to help him get away with the murder.

The CCTV footage will be shown for he first time later this week by the BBC’s In Cold Blood team.

They show how cops were able to ID Hill from the footage as he demanded CCTV tapes from filling station staff.

Police were also able to identify Brian Dickson (24) from Azamor Street and Darren Paul (24) from Lyndhurst View Avenue from CCTV pictures of the car in the garage forecourt.

The police hunt for the clues then led them to Hill’s brother Edward (22), from Southport Court, who had tried to destroy the killer’s clothes by burning them and eventually hiding the partially burned jeans and jacket in a coal bunker.

Arrogant Hill was still convinced that there was no evidence to tie him to the murder and was cocky with detectives who interviewed him for three days after he eventually handed himself in for questioning on New Year’s Day 2003 — 10 days after the attack.

But his hopes of escaping justice unravelled as cops first overheard angry discussions about the burnt clothes between Hill and his brother Edward as they sat in adjoining custody cells.

They also recovered hundreds of letters that Hill had sent to his girlfriend from his prison cell while he was on remand awaiting trial for murder.

One of the letters was effectively a signed confession, according to the cop who led the murder hunt, Detective Inspector Peter Moore.

In spite of the powerful case against him, Hill waited until the very last moment — after a jury had been sworn to hear his trial — before finally admitting

that he had murdered Mr Cupples. He is now serving a life sentence — with his minimum tariff set at 13 years.

His three partners-in-crime all pleaded guilty to assisting an offender and were sentenced to three-year probation orders.

Mr Cupples, who was working as a cook at Girdwood Barracks in north Belfast, had fought for his life for three days with his family maintaining a bedside vigil before making the heartbreaking decision to switch off his life-support machine.

His dad John told programme-makers how his son had gone on to save two other lives after he passed away by donating his liver, heart and lungs for transplants.

“He saved the lives of two other people . . . David would have liked that,” he said.

l In Cold Blood, BBC1 NI, Wednesday, 10.45pm.