New sketch of assailant linked to 1970s "Doodler" serial killings

San Francisco — Police released an age-progressed sketch Wednesday depicting an unidentified assailant linked to a cold case involving at least five stabbing deaths of gay men in the mid-1970s in San Francisco. 

The killer targeted men he met at after-hours gay clubs and restaurants in San Francisco, and police say he killed at least five men between January 1974 and June 1975. He became known as "The Doodler" because he usually sketched them before having sex and stabbing them. 

The bodies of four men were found along the beach. Another stabbing victim was found in Golden Gate Park.

Police at the time believed a suspect who assaulted two gay white men at the same apartment complex after the murders in July 1975 was a person of interest in the string of homicides. One victim who survived a stabbing assault said the attacker told him that he was a cartoonist. Police say the attacker was doodling while he and the man talked at a late-night diner. Both assault victims gave similar descriptions of the assailant, and one victim was able to help develop a suspect sketch in 1975.

The age-progressed image released Wednesday was developed from the 1975 sketch, police said. A man was detained in the assaults in 1976, but he was never charged.

Police said they were never able to positively link the assault cases to the five slayings, reports CBS San Francisco. However, in June, police said investigators with the police department's cold case unit were working on a connection.

Police also offered a $100,000 reward Wednesday for information leading to the arrest and conviction of the killer and released audio from a 1974 phone call to police reporting a body found along Ocean Beach. The caller did not give his name. On Wednesday, police asked the caller or anyone who knew who the caller might be to come forward.

Police said the man detained in 1976 remains a person of interest, but wouldn't comment as to whether that person resembles the age-progressed sketch.

An Associated Press story from 1977 quotes police saying they needed testimony from victims in order to charge the suspect. However, three survivors, including a "well-known entertainer" and a diplomat, were reluctant to "come out of the closet" to testify against him, the AP reported.

AP interviewed gay rights advocate Harvey Milk at the time about the victims' refusal to testify.

"I can understand their position," Milk said. "I respect the pressure society has put on them."

The interview with AP came just over a year before Milk, the first openly gay man elected to public office in the U.S., was assassinated.