A builder has been found guilty of killing his ex-partner in 1981 after his DNA was found on an anonymous letter blaming another man for the killing.
Osmond Bell, 60, also left traces of DNA on chewing gum used to secure the door of a utility cupboard where he dumped the body of Nova Welsh after strangling her at her flat.
Jurors acquitted Bell of murder but convicted the history graduate of manslaughter by an 11-1 majority verdict after a six-week trial at Birmingham Crown Court.
Bell denied playing any part in Ms Welsh's death, claiming to have been subjected to a "dark and terrible" four-day police interrogation in the days after her body was found in August 1981.
The former television engineer, who claimed he had been allowed to handle and read the letter during a break in police interviews, was charged with murder in August last year after a cold case review.
Jurors were told a "one-in-a-billion" DNA match to Bell was found on the a piece of gum used to secure the door of an under-stairs cupboard where Ms Welsh's body was found.
Ms Welsh, 24, is believed to have been killed in the early hours of July 27 1981, and her body was not discovered for up to three weeks.
Prosecutor Michael Burrows QC said the evidence showed Bell sent a handwritten letter to a friend of Ms Welsh after she was reported missing.
The letter - sent six days before the body was found - claimed she had been attacked at her home in Lighthorne Avenue, Ladywood, Birmingham, by a man she had been seen with on a night out.
Although the letter was apparently written by a woman, a forensic examination conducted in 2014 of the lick-seal of the envelope found an "incomplete" DNA profile matching Bell.
Mr Burrows said Bell, of Regent Road, Handsworth, could not be forensically linked to the letter in 1981.
He told the jury: "In 1981, the anonymous letter couldn't be linked to Osmond Bell - it pointed away from his guilt - but now the DNA links him to that letter.
"It was written before Nova's body had been found and therefore before anyone innocent knew that Nova had been attacked and killed, rather than going away."
The court heard that Ms Welsh had split with Bell - the father of her two children - after he tried to choke her in her kitchen.
Mr Burrows said: "In 1981, there was no evidence to link Osmond Bell with the cupboard, but now DNA links him with the lock and supports the case that he was the one who killed her and hid her body there.
"I understand that it's his case that his relationship with Nova was not volatile and that he was not violent towards her. You may think it's clear on the evidence that you will hear that things came to a head on that weekend."
Judge Patrick Thomas QC, who described the trial as "a fascinating case", will sentence Bell later.