A young man and his lover tied their flatmate’s hands together with duct tape before slitting her throat for their “perverted pleasure”, a jury has been told.

Bethany Marie Hill, 20, was found “drenched” in her own blood in the bathroom of a ground-floor flat in Stratford-upon-Avon, Warwickshire, the court heard.

Her ex-partner Jack Williams, 21, and his girlfriend, Kayleigh Woods, 23, carried out the “sadistic killing”, Warwick crown court was told.

Williams and Woods, who deny murder, tried to cover their tracks by claiming that Hill had killed herself, it is claimed.

The three were living together in the same one-bedroom flat at the time of the alleged murder on 2 February last year and the relationship was fraught, the jury heard.

Opening the prosecution case, Stephen Linehan QC told the jury the “sadistic killing” may have been carried out for “perverted pleasure”. He said: “On 2 February Williams went to work, leaving Beth and Kayleigh Woods together in the flat. He returned from work at about 1am [3 February] and during the early hours of that morning he and Kayleigh Woods took part in the murder of Beth.

“Only those two defendants know precisely what happened. Only they know precisely what role each other played. They have never told the truth. Each of them has spun a web of lies in order to conceal the truth.

“The evidence does show that the murder was not done quickly. Beth’s wrists were bound together with duct tape and a blade was used to inflict repeated cuts across the back of her neck before she was killed by her jugular vein being cut through so she bled to death in that bathroom.”

Linehan said Woods, who was assigned male at birth, had met Hill at college in Stratford and they became best friends. Woods was introduced to Williams and had a sexual relationship with him.

The court heard Hill was found partially clothed. Jurors also heard police found a Barbie doll gagged and bound, its hair coloured with felt tip pen apparently to resemble that of the victim.

Linehan said: “Kayleigh Woods had a gran and she contacted the police and told them in December Kayleigh Woods had came to her and had left with her a number of boxes and she had put them into her attic.

“Police officers opened them and one of the items they found was a doll. Somebody was fantasising about binding a woman with tape and covering the mouth with tape and created that doll.”

Jurors were told the trio had a confused relationship. At the time of Hill’s death, she was sleeping in the bedroom of the flat while Woods and Williams slept together in the sitting room.

Linehan added: “The relationship between Beth and Kayleigh Woods was not a simple one, in fact it appears to have been complicated and volatile ... They spent a great deal of time agonising about how difficult they thought their lives were.”

The prosecutor said Woods waited to phone 999 until 7.07pm on 3 February – more than 12 hours after Hill had been killed. She told the operator: “Well, my best friend is dead in my flat.”

Police officers and paramedics found Hill’s body already in rigor mortis. “When the police officer asked her [Woods] what had happened she replied: ‘She’s a mess, she’s always been suicidal and taken tablets.”

Linehan said: “All these things were lies. Beth Hill had not died as a result of cutting herself. She had been brutally murdered.”

The prosecutor alleged that although Woods appeared to be distressed during the emergency call, she was in fact “play-acting”. “You will learn during the course of this case that she is a good play-actor and a prolific and practised liar,” Linehan told the jury.

The trial continues.