Still Searching for the Zodiac Killer

He was a serial killer like no other, who terrified millions. He sent letters to police, including cipher puzzles and pieces of blood-stained evidence. Once decoded, the ciphers revealed only the arrogance of the killer who called himself Zodiac.

For almost four decades, the zodiac murders remained a morbid fascination to many and an unsolved frustration to police. Next week, a major feature film will re-ignite the story of a killer who plunged the entire San Francisco Bay Area into a state of fear.

For more than a year, beginning at Christmas 1968, Zodiac ambushed three young couples at lovers' lanes near Vallejo and Napa, Calif., and brutally executed a taxi driver in San Francisco. Police have confirmed five murders that can be attributed to the Zodiac killer, but he claimed to have committed dozens more that were never proved.

Terrifying as the murders themselves were Zodiac's letters to the police. In them, he taunted police, provided proof of his crimes, enclosed cipher puzzles and threatened to kill again unless local newspapers published his letters on their front pages.

Amateur Investigation

Robert Graysmith, then a young cartoonist with the San Francisco Chronicle, was so fascinated by the case that he began a decades-long amateur investigation into it.

"It terrified everyone, Graysmith said." Three newspapers gave their front pages to the man. I mean, that's how terrified they were."

In the film, Graysmith is played by actor Jake Gyllenhaal, and Robert Downey Jr. plays a reporter who, like the police, at first dismisses the young Graysmith.

The film details the inability of police detectives to solve the case as Gyllenhaal traces Graysmith's transformation from naive onlooker to amateur sleuth.

"I would work all day and then I'd get in my car and at two in the morning. I'd be in Vallejo, Calf., sitting in front of a house," Graysmith said.

"He was … this bold innocent," said Gyllenhaal. "He'd come up and be like, 'I need this information, I need this information, I need this information,' without even understanding that they had an emotional connection to it. These characters had lost large portions of their life in trying to figure this out. And when he came to them and asked them questions, he would open up things in them that … bothered them more and more, [because] they hadn't solved it themselves."

Investigation Turns to Obsession

"During that period I saw this fear that just gripped the staff, and this obsession," said Graysmith. "And gradually, it began to blink out, and I seemed to be the only one left interested."

Graysmith soon became more than interested; he became obsessive. He began writing a book that would later become a best-seller, but it took 10 years to finish and cost him his marriage.

Graysmith's suspect was Arthur Leigh Allen, a former school teacher who lived in Vallejo. Over the years, Graysmith gathered a mountain of circumstantial evidence placing Allen at or near every murder scene. Allen even wore a watch with the brand name Zodiac.

"To use the symbol … to wear that watch, and to be at the crime scenes and to know the victims … he would have to be Zodiac," said Graysmith.

But even with his mountain of evidence, Graysmith couldn't prove anything, and in 1993, Allen died.

Finding Fingerprints

Then, four years ago, in the San Francisco police DNA lab, Dr. Cydne Holt examined some of the Zodiac letters and made a surprising discovery. "I found a partial DNA fingerprint from a male individual who, at sometime, has had contact with the stamp," Holt said.

But when she compared it with Allen's DNA profile, she found that he was not a match.

"Based on the information that I developed, Arthur Leigh Allen could not have contributed the DNA that I detected on the stamp," Holt said.

But obsessions die hard, and Graysmith pointed out that over three decades, the Zodiac letters have passed through a lot of hands and could have been contaminated.

"I would love to have had a really good, strong DNA. You just don't know. It could be somebody that slips though the cracks," he said.

Stirring the Pot

Meanwhile, three Zodiac letters lost for 20 years suddenly surfaced during the "Primetime" investigation in 2002. These letters provided new evidence for DNA analysis. That investigation led to the report "The Search for the Zodiac Killer," which aired on "Primetime" on Oct. 17, 2002. Click here to read the original story and learn more about the Zodiac murders.

In 2003, San Francisco police de-activated the case, without explanation, but the Zodiac investigation got new life just recently, in Vallejo.

Detective Mathew Meredith said, "We've been contacted by … people indicating that they believe there was evidence out there that we could still test. So, we've taken that and run with it."

With the untested letters, Meredith hopes to develop a complete DNA profile of Zodiac, which could be compared with millions of others in various national databases.

"Hopefully, it will turn something up. And if it doesn't, this is kinda stirring the pot, and we'll see what floats to the surface," he said.

"That's what they make last chapters for," said Graysmith. "First of all, it would really round out the book. That would be fantastic. But, I mean, that would be the greatest thing in the world if they caught this guy. No matter who he is."

To this day, Graysmith is convinced he came very close -- perhaps too close -- to solving the Zodiac murders. At one point, in Vallejo, he came face-to-face with his suspect, finding him at work in a hardware store.

"He gets there and it's just two human beings … looking at each other," explained Gyllenhaal, "maybe almost in the mirror. Because both of their lives have been destroyed by it. And for what?"

"In the end, it wasn't all bad," said Graysmith. "I think, had I to do it over again, I probably would do it. Probably would. But it does grip you. It takes over your life."