This is the moment a bloodied student who stabbed a sex worker to death in a Dexter-inspired 'kill room' smirked at police. 

Benjamin Day, 20, who was obsessed with the US crime drama, had flagged down a police car as he walked along the street after the brutal murder of Maria Saceanu, 24, pictured for the first time today. 

Officers tending to Day's injured hand shortly after the killing become suspicious about his story about being bitten by a dog.

The killer is seen in later footage simply nodding as West Midlands Police officers - wearing bodycams - arrest him in hospital where he was being treated for a knife wound. 

Day – wearing a green khaki long-sleeved shirt, the same as worn by Dexter in the show – reacts angrily when they question what had actually happened. 

He claimed to have been bitten by a wild dog after cutting his hand during the 'gruesome task' of dismembering Ms Saceanu's body. 

He flagged down a passing police car after walking 'some distance' from the property when he left Ms Saceanu. 

In the footage one officer asks him: 'Where's the dog? Is it your dog?'

Day replies: 'No it is a wild dog... It just attacked me.'

The officers then ask him to sit down so they can look at his injured hand, which is wrapped in gaffer tape. 

He appears to smirk again as one female officer asks him: 'Did you wrap that yourself? Where did you get the gaffer tape from?'

Day tells them that he bought it and it was in his car but he can't remember where his car was parked. 

One of the officers, increasingly suspicious about Day's account, asks him: 'What has gone on? Have you been attacked...because I'll be honest with you, your story doesn't quite check out. So where did it actually happen?'

It comes as pictures emerged showing the inside of Airbnb where he set up his 'kill room'.  

Rooms in the semi-detached property on a residential street in Tividale, West Midlands, are still available to rent. Images show patterned bedspreads in each of the three bedrooms. 

Day, a forensic sciences student, admitted killing Ms Saceanu on the second day of his trial at Wolverhampton Crown Court yesterday. 

He had been expected to claim self-defence, asserting he set up the room at an Airbnb to film a 'tribute' to US show Dexter which he could post on TikTok. But after an hour's delay in court, he returned to the dock and appeared to smirk as he nodded to enter a guilty plea.

He was remanded into custody, with the case adjourned pending psychiatric assessments.

Day, 19 at the time of the killing in December last year, is the son of a company director. 

The court was told the University of Worcester student prepared the room as a 'tribute' to the US drama, lining it with plastic sheeting.

The show followed forensic technician Dexter Morgan, who leads a secret double life as a vigilante serial killer.

Prosecutors said he was 'fascinated' with Dexter and his actions 'were those of a copycat'.

Ms Saceanu answered a text from him shortly after 9.30pm on December 20 and drove to the Airbnb where Day had been 'preparing' since 5.30pm. The prosecution said Day had killed her within a short time of her arrival.

Another guest staying in another room at the Airbnb noticed a trail of blood and told the landlord, who called the police. 

Officers found Ms Saceanu in the bedroom lying next to the bed. She had been stabbed 78 times.

The bedroom floor and walls, as well as the bed itself, had been lined with plastic sheeting which had been stapled to the wall. A canvas knife roll containing multiple knives was discovered, as well as a staple gun and duct tape.

Day had also amassed items including an apron, a plastic visor and cleaning materials.

A Home Office pathologist said Ms Saceanu probably died as a result of wounds to her neck. She also had 'a number of wounds to her hands [which were] consistent with efforts to protect herself'. 

Detective Inspector Matt Marston, from the Major Crime Team, who led the investigation, said: 'Day had an obsessive personality and had become obsessed with the character Dexter. He planned this murder in meticulous detail.

'It was a pre-planned brutal attack on a defenceless woman lured to the room he had rented.

'Day had flagged down officers where he offered them a fabricated story about the reason why he had received an injury to his hand. Officers were suspicious and he was quickly detained.

'The details of this case shocked experienced officers and our thoughts continue to go out to the heartbroken family of Maria at this time.'