THE ex-partner of a mother-of-four has gone on trial accused of murdering her only hours after he raped and beat a lookalike.
Marvin Samuels, 31, is accused of stabbing Sharlana Diedrick 16 times, only stopping because he hurt his hand.
Derby-born Sharlana, 32, was estranged from Samuels, who denies her murder.
He does admit a sex attack on a woman only hours before Sharlana was knifed.
It was the first day of Samuels' trial yesterday and members of Sharlana's family, including her sister, Karlana, travelled to the Old Bailey in London from Derby.
The court heard his alleged attack on Sharlana happened after they argued near his home in north-west London in September 2012.
Earlier that same day, Samuels raped and savagely beat a woman at a reservoir in north-west London, which he has admitted.
Prosecutor Duncan Atkinson said that, in the later incident, witnesses saw Samuels strike Sharlana in the head several times after a blazing row over their son, then calmly walk away from the car.
Her body was discovered slumped in the driver's seat of the black Hyundai, which was parked in Harlesden. She was pronounced dead in hospital less than an hour later, on September 29 last year.
Neighbours reported Ms Diedrick screaming: "Help, somebody help, he's stabbing me."
Mr Atkinson said that, a few hours earlier, Samuels had pounced on a 42-year-old woman walking her dog along the banks of the Welsh Harp Reservoir.
Samuels claims he was "lost in space" when he dragged the woman into the bushes, raped her and beat her around the head with a bottle and a branch, and then left her for dead.
She was not found until the next morning when she was discovered naked, curled up in a foetal position rocking back and forth.
Samuels, of Conduit Way, Stonebridge, north-west London, denies attempting to murder the woman, but admits rape and causing grievous bodily harm with intent.
Mr Atkinson said: "The defence will seek to prove the defendant was suffering from a recognised mental condition that substantially impaired his understanding of what he was doing."
Opening the trial, Mr Atkinson first spoke about the attack on the woman at the reservoir.
He said Samuels had headed to the reservoir to "clear his head", then spotted the woman – a complete stranger – who bore a striking resemblance to Ms Diedrick.
He said: "She was someone in the wrong place at the wrong time."
Mr Atkinson said: "He started to talk to her and pulled her into the undergrowth and hit her.
"He directed her to remove her clothing and raped her.
"He started to choke her with a scarf and struck her head, first with a bottle and then a branch.
"He said he was feeling abnormal when he attacked her."
The woman was reported missing later in the evening by her concerned husband.
Mr Atkinson added: "She has not been able to give an account of what happened to her."
Samuels attacked the woman at about 5pm and killed Ms Diedrick at about 11.10pm, it was alleged in court.
Mr Atkinson said: "Ms Diedrick and the defendant had an on-off relationship, and had a child together.
"The relationship was volatile and had included incidents of domestic violence."
He said that on September 29, two witnesses heard a female screaming for help at 11.15pm.
Mr Atkinson said: "They both saw a black male fitting the defendant's description standing outside the car facing the female.
"One witness described seeing the male making movements with his hand towards the female's head. Both then described the male walking away from the scene."
Samuels handed himself in to police the following morning, admitting he had stabbed Ms Diedrick, and DNA samples linked him to the rape.
He told officers he and his ex-girlfriend had been rowing over their son and he had "lost it completely".
"He said he would have stabbed her more had he not hurt his hand in the attack," said Mr Atkinson.
At the time of her death, Ms Diedrick, who lived in Derby until her teens, was living in Watford and Samuels was staying with his mother.
Samuels said they had a "love-hate relationship" and claimed his former partner was "a master of manipulating people".
The trial continues.
