Conrad Roy III's Father

Prosecutors believed Michelle's words and actions caused a vulnerable Conrad to take his own life.

He described his fragile state in that video diary.

And prosecutors learn Michelle did more than send text messages to Conrad.

As deadly carbon monoxide filled the cab of his truck, Michelle was talking to him on the phone.

There were two phone calls after the last text message.

One from him to her, 41 minutes, and then one from her to him for over 42 minutes.

But how would they ever know what was said on those calls?

Detectives poured over thousands of text messages, and they got their answer.

The detective says a message Michelle sent her friend, Samantha Boardman, explained it all.

Sam, his death is my fault.

Like, honestly, I could have stopped him.

I was on the phone with him, and he got out of the car because it was working, and he got scared, and I told him to get back in.

Prosecutor Flynn says another text message to that friend made it clear Michelle knew what she'd done was wrong.

She said, Sam, I just found out from his mother that the detectives have some of his things and are going through them to see if anybody texted him or encouraged him.

They read my text messages with him, and I'm done.

His family will hate me, and I could go to jail.

And that's what was at stake on June 5th, 2017, almost three years after Conrad Roy's death.

At the Bristol County Courthouse in Taunton, Massachusetts, Michelle Carter went on trial.

The drama began almost immediately.

Instead of having the case go before a jury, Michelle, at the last minute, chose to let a judge decide her fate.