Lester Holt

And she gets very detailed.

A work alibi was familiar to Allison.

Her ex, Delbert, used it himself when Patricia Lee died in that fire.

Allison also talked about the role she would have to play if and when the plan succeeded.

You can hear her complaining that she'll have to be the grieving widow.

What do you think when you hear all of these things that are being said on these calls?

I knew that she was a terrible person.

I didn't know that she was that heartless when she said, I'm going to have to play the grieving widow for a while and oh boo hoo.

And it was just so cold.

Allison had no idea James had recorded the calls, but she was about to find out, along with thousands of strangers who would hear every word.

Not to mention a few people back in Texas who knew Allison all too well.

My initial thought really was karma.

In the years after his father's conviction for his mother's murder, John Michael struggled to find his way.

He eventually got clean, got married, and had two daughters.

John Michael had lost track of Allison, the woman he always suspected had a hand in his mother's murder.

He had no idea that two complete strangers had become obsessed with exposing Allison's plot to kill her husband.

It can't go down as a homicide.

It can't go down as anything but an accident.

James and Kate's mission had reached a tipping point.

They thought they'd recorded enough evidence to put Allison in prison for a long time.