Wikimedia CommonsDavid Toschi tracked the Zodiac Killer for nearly a decade while working in the homicide unit of the San Francisco Police Department.

In the late 1960s, a killer began terrorizing Northern California. He targeted young couples and taunted police with cryptic letters. He called himself the Zodiac. Detective Dave Toschi spent years trying to catch him.

Toschi, a sharply dressed homicide detective in the San Francisco Police Department, was known for his flashy attire and dedication to the Zodiac investigation. After the murder of a San Francisco taxi driver in 1969, the case of the Zodiac Killer he had pursued for years was finally taken from him due to a bad decision.

Ultimately, the Zodiac Killer was never caught. Toschi remained troubled for the rest of his life by both this case and the mistakes made during the process.

David Toschi Before the Zodiac Killer

David Ramon Toschi was born on July 11, 1931, in San Francisco, California. His father, Sam Toschi, worked as a school janitor, while his mother, Millie Toschi, worked in a candy factory. After his parents divorced, Toschi was largely raised by his mother and stepfather.

After graduating from Galileo High School in 1951, he joined the United States Army. He served in the 24th Infantry Division during the Korean War and helped defend the Pusan Perimeter. He was honorably discharged in 1952 and returned to San Francisco, where he joined the San Francisco Police Department.

Toschi worked for over thirty years in the department and eventually entered the homicide unit. However, where most detectives preferred to blend in, Toschi stood out. He wore bow ties, vibrant sport coats, colorful shirts, and a distinctive shoulder holster.

KRON 4/YouTubeDetective David Toschi inspired Hollywood legends like Bullitt and Dirty Harry.

Then, in the 1960s, Dave Toschi pursued the most notorious case of the era, the Zodiac Killer.

On the Trail of the Zodiac Killer

Between 1968 and 1969, the Zodiac Killer murdered at least five people in Northern California, mostly young couples. He also sent cryptic, taunting letters to the police, but managed to evade capture.

San Francisco Police DepartmentA depiction of the Zodiac killer based on the testimony of a surviving victim.

And in October 1969, following the murder of taxi driver Paul Stine — the last known victim of the Zodiac and the only one killed in San Francisco — the case landed on Detective Dave Toschi's desk.

Working alongside Inspector Bill Armstrong, Toschi became the lead investigator on the case. For years, the two detectives spent time examining evidence, interviewing witnesses, and trying to decipher the killer's cryptic messages. According to Toschi's memoir in The New York Times, he estimated that he spoke with over 5,000 people during the investigation.

Indeed, Toschi followed countless leads — but one suspect caught his attention more than others. Among the Zodiac Killer suspects, Toschi believed that a man named Arthur Leigh Allen was the most likely candidate. Toschi reportedly had a feeling the moment he met Allen, and it was said that Allen had told a friend he was writing a “novel” about a killer named “Zodiac.”

Public DomainArthur Leigh Allen's driver's license, one of the Zodiac Killer suspects.

However, investigators were unable to prove that Allen was responsible. Fingerprint and handwriting analysis failed to definitively link him to the murders, and the Zodiac Killer remained at large.

Then, in 1978, Dave Toschi was forced to resign from the case.

How Scandal Ended Dave Toschi's Pursuit of the Zodiac Killer

While searching for the Zodiac Killer, Dave Toschi attracted wide attention. He inspired Steve McQueen's character in the 1968 film Bullitt and also influenced the character Harry Callahan in the 1971 film Dirty Harry. However, in 1978, he drew attention for a different reason.

Solar Productions/Warner BrothersSteve McQueen portrayed a character inspired by Dave Toschi in the 1968 film Bullitt.

That year, Toschi's involvement in the Zodiac Killer case came to an abrupt and unexpected end. It was revealed that Toschi had sent letters to the San Francisco Chronicle under a fake name praising his performance in the Zodiac investigation.

Toschi described the letters as “a stupid thing” and “a poorly thought-out pleasure.” However, damage had been done. Toschi was removed from the Zodiac investigation and assigned to robbery detail.

Although he remained in the police force until his retirement in 1985, the scandal meant he would not rise any further in the San Francisco Police Department. Moreover, it raised questions about whether Toschi had written at least one Zodiac Killer letter himself. The detective vehemently denied this, and no evidence was found to definitively link him to the Zodiac letters.

However, even though he was removed from the case, Dave Toschi never completely distanced himself from the mystery of the Zodiac Killer.

The Unsolved Case That Haunted Dave Toschi

After retiring from the San Francisco Police Department, Dave Toschi worked in private security. However, he never forgot the Zodiac Killer case and spent many hours with former political cartoonist Robert Graysmith, who wrote two books on the Zodiac Killer.

The mystery continued, unresolved and becoming deeply personal.

In the 2007 film Zodiac, directed by David Fincher, actor Mark Ruffalo portrayed Toschi, capturing the detective's determination as he worked to catch the Zodiac Killer. Ruffalo depicted Toschi as both confident and increasingly frustrated, showing how the case wore him down over the years.

Indeed, according to San Francisco Chronicle, Toschi's friends said the case weighed so heavily on him that he developed a stomach ulcer from the stress. Toschi spent years following leads, interviewing thousands of suspects, and trying to decipher the killer's cryptic messages.

Paramount PicturesMark Ruffalo portrays homicide detective David Toschi in David Fincher's 2007 film Zodiac.

Tosci believed he knew who the Zodiac was. But without enough evidence, the case slipped through his fingers. And he never stopped thinking about it.

Every year, on the anniversary of Paul Stine's murder, Toschi would return to the quiet street of Presidio Heights in San Francisco where the crime took place in 1969. Sitting in his car, sometimes for hours, he would replay the case in his mind, wondering what he had missed.

“Why couldn’t we catch this guy?” he once asked. “That still haunts me. It always will.”

Dave Toschi passed away on January 6, 2018, at the age of 86. However, the Zodiac Killer was never identified, and the case that defined his life remained unsolved.