LAST SEPT. 13, BIFF BOWEN AND HIS wife, Cindi, were halfway through their 2,144-mile hike down the scenic Appalachian Trail, when they stopped for supplies in Duncannon, Pa., nestled along the Susquehanna River near Harrisburg. Then they headed up nearby Cove Mountain to a three-sided log shelter where they planned to spend the night. As the couple scrambled down the steep incline behind the shelter, Biff inexplicably started to feel uneasy. "Something was wrong," he says. He shifted his walking stick so he could use it as a weapon and edged his way around to the shelter's open side. Food and equipment had been strewn around wildly. And there was a body. Two.

The Bowens had stumbled onto the double murder of two experienced hikers—Molly LaRue, 25, of Shaker Heights, Ohio, and her boyfriend, Geoffrey Hood, 26, of Signal Mountain, Tenn. Hood had been shot in the head, the back and the side with a .22 caliber revolver. LaRue had been bound, raped and stabbed eight times in the neck and upper back. She had also been tortured: A boot mark was found on her left elbow, and a nylon rope had been strung around her neck.

The murders sent shock waves up and down the Appalachian Trail. The AT, as it is known to hikers, is something of a national shrine, a peaceful pathway through the mountains, where nearly 4 million people a year try to find respite from the cares of civilization. "Molly and Geoff were prepared for bears and snakes and other wildlife," says Geoff's father, Robin, a physical therapist. "They didn't know their worst enemy would be man.

Unfortunately there are incidents on the trail every year, though usually minor: fishhooks strung across the path by vandals, cars looted at trail-heads while the drivers are off hiking. But sometimes the trouble is deadly. Molly and Geoff were the sixth and seventh murder victims on the trail since it opened in 1925.

Eight days after the bodies were found, National Park rangers in Harper's Ferry, W. Va., arrested a bearded backwoodsman who matched the description of a man spotted by a dozen witnesses near the murder scene. He was wearing Hood's well-worn hiking boots and carrying his distinctive green backpack with purple side panels. Both had been stolen from the shelter. Found with the backpack were other items of Hood's—a watch, a book, a foam sleeping pad—plus a .22 caliber revolver and an 8¾-inch knife. (Tests by the Pennsylvania State Police later indicated that the gun was used to kill Geoff and that blood traces on the knife were the same AB type as Molly's.)

The suspect identified himself as David Casey Horn, 38, a tobacco-farm worker from Loris, S.C. His name and age alerted a Florida FBI agent, Brad Brekke, who read about the case in the Tampa Tribune. He had been looking for a 38-year-old fugitive named Paul David Crews, a drifter indicted in Bartow, Fla., for cutting the throat of hairdresser Clemmie Jewel Arnold, 56, in July 1986. Crews, whose biological father was named Home, had the word CASEY tattooed on his right shoulder, as did the man arrested at Harper's Ferry. A fingerprint check showed that Crews and David Casey Horn were the same man. "It's not every day you get that kind of a break in a case," Brekke says.

Pennsylvania got Crews first. He was extradited to New Bloomfield, Pa., where he is now being tried for the murders of Hood and LaRue. Perry County prosecutor R. Scott Cramer is seeking the death penalty—lethal injection—which is no comfort to the parents of either victim, "it doesn't bring Molly back," says her father, Jim LaRue, a former Baptist minister who now renovates homes. "We have a lot of anger about our loss. Bui pulling someone else to death doesn't even come close to dealing with that pain."

Both Geoff and Molly had been at home in the outdoors. He was quiet and calm, an admirer of Gandhi and his teachings; she was active and gregarious, a talented artist who in 1984 won a nationwide high school contest to design a U.S. postage stamp—a childlike drawing of a stick figure family. He received a teaching degree from the University of Tennessee at Chattanooga in 1989; she graduated magna cum laude in art from Ohio Wesleyan in 1987.

They met in Salina, Kans., as counselors in Passport for Adventure, a therapeutic wilderness program that took troubled teenagers on extended camping trips. A year ago the couple decided to pursue a mutual dream: "through-hiking" the Appalachian Trail, from Maine to Georgia. Both sets of parents approved. "I have no regrets," says Geoff's mother, Glenda, a nurse. "He was fufilling a desire, and that's what life's all about."

Their trek began on Maine's Mount Katahdin on June 3. The diary they kept jointly shows they weren't out to break any speed records. They slept late, skipped days and struggled with rain, insects, rivers, rashes and sore muscles. By the fourth day, they were fairly discouraged. "We reminded one another before we started this ordeal that there would be tough days, days we would ask ourselves, 'Why are we doing this?' " Molly wrote on June 6. "Well, we had one of those days." But soon their entries got more upbeat. "We both felt good as we went to bed," she wrote June 22. "Maybe we'll get this trail done after all!"

Paul David Crews came from a far different background. Born Paul David Horne he, was the sixth of nine children from rural South Carolina. His father, whom he rarely saw, was an itinerant mill hand; his mother abandoned the family when he was 5. He spent three years in foster homes; then, like five of his brothers and sisters, he was adopted—in his case by a couple in Burlington, N.C., who gave him his new family name.

After graduating from high school in 1972, he joined the Marines and married his high school sweetheart, Theresa Dunman. Within weeks of their marriage, she says, he tried to kill himself. "He came in for lunch one day, " she says, "and slit his wrists." The marriage didn't last. Nor did his military career; he was mustered out in under a year with a less-than-honorable discharge. After that, says his brother Donald Ray Horne, Crews became a drifter. "He disappeared for about 10 years," Horne says. "He's been pretty much a mystery all his life."

By 1986 Crews was in Bartow, working as a fruit picker. That July, Bartow Police Det. Robert Schott says, Clemmie Arnold gave Crews a ride home from Madge's bar. "What she didn't know was that Crews had been living under a railroad trestle," Schott says. Later that day Clemmie's naked body was found near the tracks about 1,000 yards from Crews's "home." Her throat had been slashed, but, Schott says, the evidence is inconclusive as to whether she had been raped.

A day later police found Crews—with Clemmie's car—at the home of Donald Ray, in Polkville, N.C. After a high-speed chase, Crews managed to escape into a wooded area. He next resurfaced in 1987 in Loris, S.C., where he worked on a tobacco farm for three uneventful years. At some point he married again; his second wife, Karen Crews, may testify for the prosecution at his trial. Then on Sept. 5 last year, for reasons still unexplained, he bought a bus ticket and headed north.

Now that Crews has been arrested, hikers are breathing easier. A month ago, the Bowens, Biff, 27, and Cindi, 30, the Virginia couple who discovered the bodies, returned to the scene of the crime; they are continuing their hike through to Georgia. "We're glad to be back on the trail," Cindi says. "It's a shame that this happened, but it's a freak thing." Jim LaRue agrees. "The ultimate insanity would be to let fear destroy the trail," he says. "They've got my daughter's life, for chrissake. Don't give them the trail too."