A convicted double murderer accused of a third killing admitted his guilt to prison officers, a court has heard.
David Burgess, 64, of Beenham in Berkshire, denies murdering Yolande Waddington, 17, in the village in 1966.
Reading Crown Court heard he confessed twice to Yolande's murder while in jail for the murder of two girls in the village, in 1967.
He was arrested last year after DNA tests on items at the scene matched his genetic profile, the jury heard.
Prosecutor John Price QC said the DNA had smaller than a "one in a billion" chance of belonging to someone other than Mr Burgess, according to the scientist who tested the sample.
The trial also heard how, when accused during a police interview in December 1969, Burgess had smiled and said: "You will have to prove it."
Yolande was a nanny who had moved to Beenham a few days before she was murdered.
She was last seen alive at the Six Bells pub on the evening of Friday 28 October that year.
Her body was discovered in a ditch beside a farmer's barn two days later.
The trial continues.