Advances in forensic science helped police link a man to a rape carried out 25 years ago, a court has heard.
Nigel Palmer-Batt, 49, from Hanham, Bristol, raped a woman in her flat in 1979, Bristol Crown Court was told.
The inquiry floundered after semen swabs taken from the victim matched more than 60% of the population.
The court heard how semen left on the victim's underwear now provided a DNA profile matching a sample provided by Mr Palmer-Batt. He denies the charge.
Mr Palmer-Batt was arrested in June last year, the court was told..
New samples provided by him matched up with semen found on the underwear.
Nicholas Gerasimidis, prosecuting, said: "The probability of this matching up was one in one billion."
Mr Gerasimidis told the court that on the night of 2 June 1979, the victim, who cannot be named for legal reasons, had been out in Bristol with friends.
The woman, who worked in a fabric shop in the Bedminster area, had returned home at 2am.
She undressed, got into bed and was about to fall asleep when her bedroom door opened.
Giving evidence behind a screen, she told the court how she had looked up from her bed and saw a man standing at the doorway.
The man then walked over top the bed and put his hand on her throat.
"He said if you move I'll kill you and I did at the time think he was going to kill me," the victim said.
The court heard the woman was then raped.
Afterwards, she went straight to the police to report the rape, swab tests were taken and her clothes examined for forensic evidence.
In a police interview Mr Palmer-Batt, a musician, said that at about the time of the rape he had had a one-night stand on his 24th birthday but couldn't remember the girl's name.
He said sex with the woman had been consensual.
The case continues.