Like a cowboy loosely holding the reins, Larry Weatherman steers up Deer Creek Road with his left hand on the wheel, his right arm ready at his side. His upper body rocks with the motion of the pickup as he navigates the dirt road’s gauntlet of potholes and rocks. Since his retirement from the Missoula County Sheriff’s Department in 2000, Weatherman has adopted the bushy white mustache and Stetson of a gentleman rancher. But on a snowy Saturday in March, he has driven his two passengers the 50 miles down from his 20 acres above Montana’s Seeley Lake to revisit the forlorn woods that served, three decades ago, as the dumping grounds for Montana’s most notorious serial killer.

A gust of snow hits the windshield. Through the swirl, Weatherman spots a narrow break in the pine and fir trees lining the road. He pulls into a shallow ditch and opens his door. “He liked to take his girlfriends up here to party,” he says.

Weatherman was a young officer in 1974 when he investigated the first in a series of gruesome murders that ended a way of life in Missoula, a place where people had left their doors unlocked and women felt comfortable walking home alone from the local bar. The first victim was a preacher’s wife found gagged, bound, and shot in the basement of her home, her husband’s handgun jammed between her legs. In addition to questioning the husband, Weatherman briefly suspected a high-school boy who neighbors had spotted in the victim’s backyard that day. A grand jury found insufficient evidence to charge either suspect.

Over the next 12 years, the seemingly random murders continued. Three teenage girls and a married couple were killed, and the town suffered a spate of home intrusions thought to have been thwarted rapes. Then the improbable happened. In 1986 the husband of a would-be victim, already trussed and stabbed, managed to break free and kill 30-year-old Wayne Nance in a bloody struggle. Nance, a baby-faced furniture deliveryman and part-time bouncer, was the high-schooler Weatherman had suspected in 1974. Postmortem searches of Nance’s bedroom and his father’s house uncovered evidence of at least three additional murders and of other break-ins.

But hope for further information about the murders died with Nance. Weatherman was left with the unidentified remains of two young victims. One of them was “Debbie Deer Creek,” a teenager whose skeleton he had chiseled out of a frozen grave alongside Deer Creek Road some 21 months before Nance’s death. Several strands of dyed hair enabled Weatherman to connect her to a photo of a dark-haired drifter that bar patrons knew as “Robin” before she disappeared a few weeks after moving in with Nance. Weatherman sent out scores of bulletins to the FBI and regional law-enforcement agencies. But the girl’s picture and street name failed to locate family.

It would take more than hair strands and a faded picture to identify Debbie Deer Creek. It would take technology—still two decades away—that could extract minute amounts of fractured DNA to reveal an indelible link to a victim’s family. It would take one brother’s unceasing search to find out what happened to his runaway sister. And perhaps most of all, it would take the U.S. Department of Justice’s slow but horrifying realization that there may be far more serial killers on the loose in America than anyone had ever expected.

For two decades, a facial reconstruction made from Debbie Deer Creek’s skull sat on top of Weatherman’s bookcase facing that of another girl, “Christy Crystal Creek,” discovered by a hunter two miles farther up the same mountain road above Nance’s home. Weatherman is still troubled when he thinks of the nameless girls. “I know somebody once cared for them,” he says.