ALCOVA, WYO. -- Officially, the death of Rebecca Thomson Brown, who plunged 112 feet from a bridge onto rocks along the North Platte River, is classified as an accident or suicide.

But Natrona County Sheriff David S. Dovala says he is convinced that it was murder, 19 years after the fact.

Brown, 37, perished in the dying sunlight July 31 after falling from the very spot above Fremont Canyon where, in 1973, two men raped her and threw her and her stepsister, 11, into the abyss on a pitch-black September night.

The younger girl died, but Becky Thomson survived with multiple pelvic fractures. Or at least, she remained alive.

"She was raped and murdered 19 years ago, but she didn't die until" this July, Dovala said. "If that hadn't happened to her, she would be alive today and happy. There's no doubt about it."

The ordeal that began and ended for Becky at the 60-foot-long iron trestle amid the red-rocked buttes, sagebrush and scrub cedar of the central Wyoming highlands devastated a family and has passed a legacy of suffering and trauma to a new generation. Years after it was committed, the crime turned survivors into victims.

"They killed two girls," Dovala said of the men still imprisoned for murdering Becky's stepsister, Amy Burridge. "But they ruined a family."

With his laconic speech, broad shoulders and neatly trimmed mustache, Dovala seems born to the part of a western lawman. He too has been touched by the tragedy.

Dovala was a Casper police detective who began the search for Becky and Amy when they were reported missing and who tracked down their abductors, arresting one. He remained close to Becky over the years, and at her 1989 wedding, he stood in for her stepfather, an oil rigger unable to get away from a drilling site. On July 31, he was at the bridge directing recovery of her body.

"I knew she was troubled, but this was a complete surprise to me," he said.

Dovala can recite details of events that took Becky to the Fremont Canyon Bridge the night of Sept. 24, 1973 -- how she and Amy had gone to a Casper Mini-Mart convenience store in the family's Ford station wagon for groceries, how they emerged to find a flat tire and accept a lift from two men in a white car.

Throughout the night, Becky testified at the trial of her assailants, the two men terrorized her and Amy as they drove mountain roads around Casper, along desolate countryside where deer and antelope roam dusty fields, where vast expanses surround farmhouses and where road signs warn: "Open Range; Loose Livestock."

They ended up at the bridge about 35 miles southwest of Casper, just outside this settlement of about 100 people. As Amy was taken from the car, Becky testified, she turned to her stepsister and said, "I love you, Becky." She said she never saw her again. Weeping, she told the court: "That little girl was so brave."

Amy hit the water head first, according to the autopsy.

Becky was raped by both men, she testified, and thrown from the bridge. "Make sure she's going to die," she recalled one assailant saying. "Make sure she's going to be dead."

But Becky hit an outcropping of rocks about 40 feet down, redirecting her fall toward the middle of the river, where the water was deeper. She swam ashore and hid among the rocks. The next morning, unable to walk, she dragged herself backwards up the nearly vertical canyon walls to the top. There, she was found by an elderly Casper couple going fishing.

They drove Becky 10 miles along narrow, twisting county roads to Sloane's, a small store and gasoline station in Alcova, where a sign offers "Gas/Gro.-Pop/Bait," and help was summoned.

Becky recovered from her physical injuries and seemed to move on with her life.

After working briefly as a parking enforcement officer for Casper police, she sold advertising time for local radio stations. She married and had a daughter, experiencing difficulty both with conceiving and giving birth because of her injuries, friends and associates said. They described an outgoing woman who loved practical jokes and always sent colleagues cards on their birthdays.

"She was a real bubbly, likable person, a good, good, decent person," Dovala said.

Jack Case, her stepfather, said that, "with all the tragedy she's been through, she did her best -- she was a very strong girl -- she did her best to make other people happy."

But her struggle continued -- with alcohol and with depression -- friends and associates said. Her marriage ended in divorce. She sought professional help. "She recovered physically," said James W. Thorpen, the county coroner and physician who performed autopsies on Amy in 1973 and on Becky Aug. 3. "Psychologically -- that's another question."

Dovala said, "She got progressively worse through the years."

Other family members also bore the scars. A sister suffered a miscarriage at the time of the first crime, according to friends.

Her assailants' death sentences were commuted to life in prison and, Dovala said, "She had a fear when these guys came up for parole that they would get out. It really tormented her."

But most of all, Dovala said, she was haunted. "She felt bad that her sister died and she didn't," he said. "She had some guilt."

At a sweltering memorial service last week in Casper, Joseph P. Murphy, an internist who treated and counseled her, said, "Becky, have no guilt about Amy. As those of us who knew her well know, she was troubled so that it was Amy, not she, who was taken that first night. Becky and Amy are at last together again."

When Becky first came to see him professionally in 1985, he recalled, she wrote on a form: "I want to be normal again." At the service, he spoke as if to her, saying, "Becky, you were normal. Who of us here today could not live through her awful experiences and not bend and not break?"

No one knows what she was thinking on the night of July 31 as she drove in her brown Buick sedan with her boyfriend, whom authorities will not name, and daughter, Vail, 2, ending up at the Fremont Canyon Bridge. She was legally intoxicated, autopsy results showed this week. Also, friends and associates said, she recently stopped taking anti-depressant medication.

She and her boyfriend, who is not a suspect, parked and walked onto the span to virtually the spot from which Becky and Amy had been hurled 19 years before, Dovala said. The sun was setting on a clear and mild evening. They sat on the three-foot-high railing and talked. Authorities will not disclose the nature of the conversation but say it gave no inkling of what was to come.

About 9 p.m., Dovala said, the boyfriend began walking to the car with Vail. He heard a loud crash, turned and saw that Becky was no longer there. He ran to the edge of the bridge and saw her body in the clear, green water.

She had tumbled along rocks on the canyon wall before landing, face down in water about three feet deep, according to the autopsy. Her body was battered from hitting the wall. Her neck was broken. She struck the water so hard that her clothes left impressions on her body.

Her boyfriend and daughter then sped the same 10 miles along the same narrow, twisting county roads that Becky had traveled in 1973 with the Casper couple to Sloane's to call for help.

Dovala was working at the Central Wyoming Fair and Rodeo at the fairgrounds outside Casper when the call came. "I just couldn't believe it," he said.

By the time he arrived at the bridge, a sudden thunderstorm was unleashing torrents of rain as lightning flashed and thunder roared. "It was really eerie," he said.

Five days later, Dovala was one of several hundred people who packed First Presbyterian Church on City Park for the memorial service. People entered in bright sunshine, eventually filling the pews and standing along the back and side walls.

They heard Murphy tell Becky's mother and stepfather: "As you already know from the death of Amy 19 years ago, the loss of a child is the ultimate loss." Becky's death, he said, was "the final result of what happened that night so long ago."

When Dovala and the others filed out onto South Wolcott Street, they discovered that another sudden thunderstorm had arrived and a stiff wind was whipping fat raindrops through the air.