Police released sketches of serial killer The Doodler, including a mock-up of what he may look like today (San Francisco Police Department)

Police in San Francisco have offered a $100,000 reward to identify The Doodler, a suspected serial killer who targeted gay men in the 1970s.

The San Francisco Police Department put out an appeal on Wednesday (February 6) seeking to uncover new information about the suspected serial killer, who is believed to have stabbed at least five gay men to death.

The re-opened cold case will probe several violent assaults on gay men between 1974 and 1975.

Five white gay men were found murdered during the period, with the bodies of four victims found along the beach, and one found in a park.

Police offer $100,000 reward to identify The Doodler

Two gay men also survived violent attacks believed to have been carried out by the same suspect, with one victim recalling that he had met the man drawing caricatures at an all-night diner—giving rise to the nickname The Doodler.

Police mock-ups have been released based on the description of the attacker given by a surviving victim, alongside an age progression sketch of what the suspect may look like now.

The suspect is described as an African-American male, around 5-foot-11, who was aged 19-25 at the time of the attacks.

Homicide investigators are offering a $100,000 reward “for information leading to the arrest and conviction of the assault suspect.”

DNA evidence related to the case has been submitted for testing, and officers also released audio of a call to SFPD dispatch reporting a body had been found. Police are looking to trace the unidentified person who made the call.

There could been other serial killer victims, police say

Officers believe there is a “likelihood” of additional victims who may have survived attempted attacks but have not come forward to report the incidents.

At the time, the serial killer case gained the attention of San Francisco gay community leader Harvey Milk, who would go on to be elected to the San Francisco Board of Supervisors in 1978 and was assassinated the same year.

Milk said he understood why other potential victims had not come forward, telling Associated Press in 1977: “I can understand their position, I respect the pressure society has put on them.”

A release explained: “The SFPD Homicide Detail is actively working this cold case. Anyone with information is asked to call the SFPD 24 hour tip line at 1-415-575-4444 or Text a Tip to TIP411 and begin the message with SFPD. You may remain anonymous.”

According to USA Today, police commander Greg McEachern said at a press conference: “The interest in this case now is no different than it is for all of our cold cases.

“We take a look at cases that we believe are solvable and cases that the victims have never had justice.”

Police in Toronto also previously re-opened a probe into unsolved 1970s murder cases in the gay community.

Toronto Police Department confirmed in April 2018 that officers would review the “outstanding cold cases from the Gay Village in Toronto.”

Between 1975 and 1978 there was a total of 14 murders of gay men in Toronto, many of whom were murdered in violent attacks.