Mary Louise Day was a girl that lived in seaside.

In about 1981 lived in seaside.

In about 1981,

she disappeared. What do you mean she disappeared?

She disappeared off the wrong in the house.

Mary Day is my sister.

One day Mary was in California and then she was gone.

Laying about one night with Kathy, I asked her, you know, I was like, what happened with Mary, you know?

And she was like, shh, don't say anything.

We're not allowed to talk about Mary.

When I was 18 and I was like, I can... Don't say anything. We're not allowed to talk about Mary.

When I was 18 and I was like, now I can, you know, go and try to find her.

It was a very hard case to deal with.

Other than the family, nobody knew she was gone gone didn't seem to really concern them she started running away you turn around she was gone you turn around she was gone I've never seen a case like this

my mother told me that there were a lot of places in california I've never seen a case like this.

My mother told me that there were a lot of places in California that you could bury a body and they'd never be found.

I started believing she was murdered.

The dogs went into the backyard. We just had an indication from the cadaver dogs that there was human remains there.

And our guys started digging and my heart was pounding.

We were looking for a little girl's body body and we found a little girl's shoe.

William told me that he didn't kill Mary Day,

but his wife told him that he was possessed that night,

...