On New Year's Eve in 1980, Karen Potak, a student at the University of Wisconsin celebrated with her sister in Minnesota's Twin Cities.

The girls were both celebrating on University Avenue, which runs the stretch between

St Paul and Minneapolis.

They'd gotten separated a little earlier in the night, but they didn't let that stop

them from enjoying the evening. When the clock struck midnight, the festivities slowed down,

and Karen decided to call it a night.

At around 3 a.m. the St. Paul police received this call.

Cales, please, this is an emergency police and a squatter,

pierce on the road, Malenburg Street Company Machine Shop,

please, in the Netherlands too, there's a girl who says.

Can you tell me what happened to?

There's hurry, there's a...

She's laid on the ground in the back, by the railroad tracks, by the airboat tracks, by the airboat train.

What's the address?

I don't know.

Who are you?

Hello?

From A&E, this is cold case files.

Officers responded to the call and found Karen and a snowbank near some railroad tracks.

She was naked, badly beaten, and her skull had been cracked. Karen survived but was cognitively impaired, and she had no memory of who had tried to kill her.

In June of 1981, the same weepy voice was on the other end of a 911 call.

Oh, you're fucking, you finally, I just kept somebody with an nice pick. I can't call myself. I can't come in somebody.

...