With his natty wardrobe, Mr. Toschi was for many people the public face of the investigation as the case took twists and turns over the years.
In 1978 he became one of those twists himself: He was removed from the case after revelations that in 1976 he had sent several letters praising his own work to a San Francisco newspaper writer under fake names.
“It was a foolish thing to do,” he acknowledged at the time.
In the years since, Mr. Toschi’s name would still be invoked whenever the case resurfaced in the news, as it did in 2001, when an effort was made to apply DNA testing to some of the evidence. The results of that testing did not match any suspects.
“Looking back, I feel mostly frustration,” he told The Los Angeles Times. “That case took so much out of me.”
David Ramon Toschi was born on July 11, 1931, in San Francisco. The son of Sam Toschi, he was raised largely by his mother and stepfather, Millie and Mario Peri.
After graduating from Galileo High School in San Francisco in 1951, Mr. Toschi went into the Army. He spent about a year in Korea during the war there, his daughter said. He entered the police academy after his military service and joined the San Francisco Police Department in July 1953.
In an age of somber suits, Mr. Toschi cut a distinctive figure with his clothing choices.
“He had his own sense of style — lot of bow ties, lot of loud sports coats,” his daughter said in a telephone interview. “Never wore a white shirt. Always a colored shirt.”
Mark Ruffalo portrayed Mr. Toschi in David Fincher’s 2007 movie about the case, “Zodiac,” for which Mr. Toschi was an adviser.
When she first viewed the film, Ms. Toschi-Chambers recalled, “I saw Mark Ruffalo and said, ‘Oh, my God, did they ask my dad for one of his jackets?’ ”
Mr. Toschi was a personality in the police department even before his involvement with the Zodiac case, so much so that Steve McQueen had borrowed from him for the fictional police officer he played in the 1968 movie “Bullitt.”
“They literally were filming in my dad’s office,” Ms. Toschi-Chambers said. “My dad took off his jacket, and Steve McQueen said, ‘What is that?’ And my dad said, ‘That’s my holster.’ And Steve McQueen told the director, ‘I want one of those.’ ”
Clint Eastwood also drew on Mr. Toschi for his portrayal of the title character in “Dirty Harry,” Don Siegel’s influential 1971 movie about a San Francisco police inspector, Harry Callahan, who hunts a psychopathic killer. Mr. Toschi, though, was bothered by Callahan’s penchant for administering his own brand of justice. He is said to have walked out of a screening of the movie, which was released when the Zodiac investigation was in full swing.
“He couldn’t take it,” Mr. Ruffalo, who spent time with Mr. Toschi preparing for his “Zodiac” role, said in a 2007 interview with the website Collider. “It was so simplified.”
Mr. Toschi’s daughter said he always thought that a suspect named Arthur Leigh Allen, who died in 1992, was Zodiac. But, unlike Harry Callahan, he and his fellow officers were bound by the evidence.
“If you get into who these cops were,” Mr. Ruffalo said in another 2007 interview, “you realize how they have to take their hunches, their personal beliefs, out of it. Dave Toschi said to me, ‘As soon as that guy walked in the door, I knew it was him.’ He was sure he had him, but he never had a solid piece of evidence. So he had to keep investigating every other lead.”
In a 1978 interview, Mr. Toschi estimated that he had talked to 5,000 people during the Zodiac investigation. His letter-writing misstep not only took him out of the investigation that year, but also brought a more serious accusation — that he might have written a letter from around that time that claimed to be from the Zodiac killer. He vigorously denied that speculation.
Other letters claiming to be from Zodiac turn up periodically, most of them hoaxes, and new theories and even confessions surface from time to time. The case has inspired numerous books and episodes of true-crime television shows, including a five-part series on the History channel that concluded in December.
Mr. Toschi retired in 1985 after 32 years on the force. He worked in private security afterward. In addition to Ms. Toschi-Chambers, he is survived by his wife, the former Carol Bacigalupi, whom he married in 1957; another daughter, Karen Leight; and two granddaughters.
“I’ll never forget our long lunches discussing the case over ‘Dirty Harry’ lemon meringue pie and fries at the Copper Penny on Masonic,” he said by email, referring to a dessert at a now-defunct San Francisco coffee shop.
“Dave Toschi cared about the victims far more than catching the Zodiac,” he added, “and in this he never failed.”