A sketch of a suspected serial killer dubbed “The Doodler” has been released more than 40 years after the brutal murders of five men.
Authorities in the US say they hope to find justice for the victims of the “horrendous homicides” which took place in San Francisco in 1974-75.
Police believe the killer stabbed to death at least five men as he terrorised the California city’s gay community.
He became known as The Doodler after a victim who survived an attack told police the man was doodling while they talked at a late-night diner, and that he was a cartoonist.
At a news conference, police released two images that showed a 1975 sketch of the man and an “age-progression” showing what he might look like now.
A $100,000 (£77,000) reward is also being offered for information which leads to his capture.
“In the 1970s, this was gripping the gay community and San Francisco,” said police commander Greg McEachern.
It is one of several cold cases being re-examined after the capture last year of suspected “Golden State Killer” Joseph DeAngelo through DNA analysis.
Police have submitted DNA samples from some of the 1970s crime scenes in the Doodler case and are waiting for results from a lab.
The Doodler killer targeted white men he met at after-hours gay clubs and restaurants in San Francisco.
He usually sketched them before having sex and stabbing them.
The bodies of four men were found along a beach, while another stabbing victim was found in Golden Gate Park.
In 1977, police reportedly said a suspect at the time could not be charged because three survivors, including a “well-known entertainer” and a diplomat, were reluctant to “come out of the closet” to testify against him.
The Associated Press interviewed gay rights advocate Harvey Milk at the time about the victims’ refusal to testify.
“I can understand their position,” Mr Milk said. “I respect the pressure society has put on them.”
The interview was published just over a year before Mr Milk, the first openly gay man elected to public office in the US, was assassinated.
The Doodler killer is described as an African-American male, about 5ft 11in tall, and with a lanky build. He was likely in his early 20s during the attacks.
At the time, a witness was able to give investigators a description of the attacker, leading to a man being detained in 1976 but never charged.
Mr McEachern said police have interviewed the man since returning to the case and he remains a person of interest.
His name was not released and authorities declined to say if he resembled the man in the sketches.