Chilling newly released police bodycam footage shows the moment a forensic science student obsessed with the crime show “Dexter” was busted for murdering a sex worker in a “kill room.”

Video released after Benjamin Day pleaded guilty Tuesday, just two days into his murder trial, shows him trying to convince UK cops he had been attacked by a wild dog — when he had actually stabbed his Romanian-born victim, Maria Saceanu, 78 times and tried to dismember her after luring her to an Airbnb.

But the killer, now 20, injured his hand during the attack, which happened on Dec. 21 last year, and was forced to flag down cops.

“Where’s the dog? Is it your dog?” an officer asked.

“No, it’s just a wild dog,” Day, who was wearing a khaki shirt similar to that of the character Dexter Morgan, said. “It just attacked me.”

Day’s bloodied arm was examined and he expressed relief he still had four fingers — before his narrative fell apart.

“Where did you get the gaffer tape from?” a curious officer asked.

“I bought it,” Day quickly responded before claiming the attack happened an “hour or two” ago and that the tape was from his car. He couldn’t remember the location of his vehicle.

“What’s gone on, have you been attacked?” a no-nonsense officer asked. “I’ll be honest with you, your story doesn’t quite check out.” 

“It was a wild dog or fox,” Day said, but he couldn’t explain where it happened.

The bodycam then panned to him lying on a gurney, where cops told him he was arrested on suspicion of murder. His left hand was wrapped in bandages and he was clutching his phone in the other.

Day was arrested just after 3:40 a.m. – around 80 minutes after the rental’s landlord called cops reporting blood on the stairs inside the property located in Tividale.

Day “planned this murder in meticulous detail, revealing he had an “obsessive personality and had become obsessed with the character Dexter,” West Midlands Police Detective Inspector Matt Marston said.

He lured Saceanu, 24, to a plastic-lined room and carried out the “pre-planned brutal attack” on the “defenseless” victim, Marston added.

The bed, the floor, and the walls had already been covered with a plastic sheet stapled to the wall before he went about the murder. Day also had an apron, plastic visor and cleaning materials.

A canvas knife roll containing several blades, a staple gun, and duct tape were all found at the scene after an injured Day fled.

“He had prepared himself to kill her,” prosecutor Rachel Brand said. “He had planned to dispose of her body without leaving signs of what had happened and he planned to get away with it. But it all went wrong and he was caught.”

Day initially entered a not guilty plea, but abandoned that position just two days into trial.

He will be sentenced on Dec. 4 where he faces life imprisonment.