Gary Stewart had spent a lifetime yearning to know his birth father. But on the night in 2004 when Stewart finally glimpsed what he believes is that man’s true identity, all he felt was revulsion. “A documentary came on TV about a serial killer, some guy called the Zodiac,” recalls Stewart, standing in the kitchen of his Baton Rouge home as tears well in his eyes. A 35-year-old police sketch of the suspect flashed on the screen. “Hey, Dad,” shouted Stewart’s 10-year-old son Zach. “That looks like you.” Stewart, who had learned his father’s name two years earlier and was trying to discover more about his life, ran into his bedroom, grabbed his only photograph of his dad, then raced back to the TV, staring at the two faces. “No,” he told his son, feeling his stomach twist into a knot. “It’s not me. It’s … it’s my dad.”
Stewart desperately didn’t want to believe what his gut told him was true. But the 51- year-old electrical engineer is now convinced that evidence he found in the course of his “painful” 12-year journey – which involved interviews with more than 500 people, including handwriting and fingerprint analysts – proves beyond a doubt that the infamous, never identified Zodiac killer, presumed responsible for six murders in California in the late 1960s, was his father. “This is the last thing I wanted to find out,” says Stewart, whose discoveries are detailed in his new book The Most Dangerous Animal of All. “I really just wanted to find out who my dad was.”
Stewart’s unsettling odyssey began shortly after Judith Gilford reached out to her long-lost son in 2002, informing him that she was his birth mother. Stewart, who’d been adopted as a child by a family he calls “loving, wonderful,” soon met with Gilford in San Francisco and sat dumbstruck listening to her story.
His mother, he learned, was 14 when she fled her chaotic home and ran off with a scholarly 27-year-old rare-book salesman named Earl Van Best, Jr. The unlikely duo spent months on the run, ending up in New Orleans, where Gilford gave birth in February 1963.
The couple’s relationship soon soured and, according to police documents, Best often placed their infant “in a footlocker with the lid closed” because he didn’t like to hear the boy cry. A month after the birth, Best abandoned the boy – against the wishes of his confused, frightened young mother—in a Baton Rouge apartment-building stairwell.
“I don’t think I ever want to know this guy,” Stewart thought, especially after he learned that Best spent several years in San Quentin for the statutory rape of the underage Gilford, who left him soon after he abandoned their son. But he wanted to know the facts, so his mother reached out to the San Francisco Police Department, where her late second husband had worked as a homicide detective, asking if they could help her son learn more about Best, who had seemingly vanished.
“She called me one day,” recalls Stewart, “saying officers had refused to divulge what was in my father’s police file because it was so ‘heinous, it would destroy us’ both.”
Stewart became “consumed” with learning what could be contained in his father’s files, which police repeatedly refused to share with him. He discovered through public records, relatives and former acquaintances of his father’s that before he died, in Mexico City in 1984, Best had nearly beaten his first wife to death. When Stewart saw the police sketch of the Zodiac staring at him from his TV screen that night in July 2004, “I didn’t want to believe it and used every clue I could find about the Zodiac to disprove it,” he says. “But over time everything fell right into place.”
Among the evidence linking Best to the Zodiac: handwriting. Stewart had forensic document analyst Mike Wakshull compare Best’s writing on his marriage license to writing found in the 20 or so taunting, cryptic letters the serial killer sent police. “I’m virtually certain they were written by the same person,” says Wakshull. A fingerprint specialist also found strong similarities between prints on record for Best and a blood-smudged print found at one of the Zodiac’s crime scenes.
Not everyone is convinced. Stewart’s own mother – who never saw Best after his 1963 arrest and whose second husband, ironically, worked on the San Francisco Police’s unsuccessful search for the Zodiac – says she “cannot imagine that Van could be capable of such violence.” A spokeswoman for the police department, which Stewart claims has repeatedly declined to compare his DNA to the Zodiac’s, isn’t commenting on the new findings, telling PEOPLE, “It’s still an active investigation.”
Stewart remains puzzled over the department’s reluctance to test his DNA. “I still don’t have all the answers,” he says. “I never will. But I’ve got all the answers I want, and I’m truly ready to get on with my life.”