In 1973, Becky Thomson was brutally attacked on a bridge. 19 years later she died there.

On July 31, 1992, Becky Thomson Brown took a trip to Fremont Canyon Bridge, outside of Casper, Wyoming.

There, the 37-year-old fell more than 100 feet to her death, into the choppy waters of the North Platte River.

Some believe her death was 19 years in the making.

On September 24, 1973, Becky, then 18, and her 11-year-old half-sister, Amy Burridge, drove to the local convenience store.

According to the Washington Post, it was 9pm and the two sisters were there to pick up some groceries for their family.

Around 30 minutes later, Amy called home. She told the girls’ mother that the car had a flat tire, but two “nice men” were going to give them a lift home.

Instead of dropping the sisters home, the men, Ronald Kennedy, 27, and Jerry Jenkins, 29, forced them into their car at knife point.

They then drove the girls out to the Fremont Canyon Bridge.

Once they reached the bridge, one of the men forced Amy out of the car. According to the New York Daily News, Amy’s last words were, “I love you, Becky”.

Becky never saw her little sister again.

The man walked the 11-year-old to the middle of the bridge and then pushed her into the water below.

The men then took turns raping Becky before walking her to the middle of the bridge, telling her she was about to meet her sister.

After a struggle, they pushed the 18-year-old over the railing and into the churning waters below.

Miraculously, Becky survived.

The next morning, an elderly couple who were travelling to the bridge to go fishing, came across a bloody and beaten Becky.

She was naked from the waist down and slumped across the side of the road.

“I was raped and thrown off the bridge, and my little sister too,” Becky told them.

Becky was able to describe her attackers, and the men who were well-known to the local police, were quickly arrested and charged.

After less than five hours of deliberation, a jury found them both guilty of assault, rape and murder. They were both sentenced to death. In 1977, their death sentences were reversed and they were given life behind bars.

But really it was Becky who was handed the death sentence.

Once her physical wounds healed, the teenager tried to move on with her life.

She ended up relocating, she married and had a child of her own. But Becky could never truly leave the demons of her past behind.

She came back to Casper, Wyoming divorced and in debt.

In 1992, worried that Kennedy and Jenkins might succeed in their bid for a new trial, Becky returned to the scene of the crime.

At dusk, she travelled out to Fremont Canyon Bridge with her boyfriend and two-year-old baby.

No one really knows what happened next. One moment Becky was standing on the edge of the bridge, the next moment she was gone.

“She was raped and murdered 19 years ago, but she just died Friday,” David Dovala, the detective assigned to her case in 1973, told reporters.

“If that hadn’t happened to her, she would be alive today and happy. There’s no doubt about it.”

Dovala had remained close to Becky over the years and had even walked her down the aisle at her wedding.

He knew she was struggling but never expected such a grim outcome. He believes Kennedy and Jenkins killed both girls that night.

“They killed two girls,” he told the Washington Post. “But they ruined a family.”

Almost 50 years on, the town of Casper, Wyoming, is still haunted by the story of the two sisters and the bridge.