This episode contains descriptions of sexual violence. It may not be suitable for everyone.

Please use discretion.

I was working as a detective and I was called and myself and my partner went to the where the girls car was and surveyed the scene.

We could see where the tire on the car was cut purposely and then we just started going door to door and asking questions.

Anybody saw anything.

This is David DeValla, a retired detective with the Casper Wyoming Police Department.

Around 9 p.m. on September 24, 1973, 18-year-old Becky Thompson and her 11-year-old sister Amy drove to the grocery store in Casper.

When they came out of the store, they found the right rear tire on the family's station wagon was flat. They used a payphone to call their mother.

They were in a quandary on what to do and then these two guys pulled up and offered to help them.

The men said they would repair the tire and then one of them pulled out a knife.

They took them at knife point and took them in their car and that was the start of a trip through hell for them.

The two men drove Becky and Amy 30 miles outside of Casper to a place called Fremont Canyon.

Fremont Canyon is a striking narrow red rock canyon with steep walls and a long bridge.

The men stopped the car at the foot of the bridge.

On this day, it was really the darkest night. There was no moon or anything and there's an area there, a rest area.

It's really way off the, you know, out of sight and everything, unless you're driving through there.

One of the men took 11-year-old Amy out of the car. He walked her to the middle of the bridge.

Becky was told to lay down in the back seat and couldn't see anything.

When the man returned, Amy was not with him. Both men then proceeded to rape Becky.

And then they took her out of the car. They took her to the bridge and walked her on the bridge and then they went to push her over and she fought.

So she wouldn't get thrown over. She fought but then they were choking her and so she figured that she'd just as well let them push her over and take her chance as otherwise they were going to strangle her.

So they pushed her over and as she, it's 112 feet up from the bottom of this canyon, she hit the water.

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