On June 21st, 1978, 22-year-old Carla Brown was found brutally murdered in the basement of her home.

It looked as if the killer had committed the perfect crime.

And police could find very little evidence.

But years later, investigators noticed something on a crime scene photograph that had previously been overlooked.

The killer had left behind a clue.

Yeah. behind a clue. 22-year-old

and her fiancé, a man will call Mark Hart,

had recently purchased a home together in Wood River, Illinois. Although the couple

had a rocky past, friends and family saw this as the beginning of a new phase in their

relationship. Carla Brown was a beautiful young woman, was very popular in her hometown in the

Wood River area. It was one of those girls that everybody knew.

Girls liked her, guys liked her. She was just one of those people that was special and everybody

recognized that.

On June 21st, Carla Brown took the day off from work to unpack.

Yes, the house is great.

And spoke to one of her friends on the telephone.

Maybe we can have you ever for dinner.

They had talked for a few minutes.

In fact, we even talked about getting together later on that afternoon.

Wait a second. I just heard something at the door.

And Carla interrupted the conversation and said, listen, I'll have to call you back.

I'll see you later. There's somebody at the door.

...