Lester Holt

Reporter Alan Jennings was in the courtroom.

Prosecutors say he was obsessed, jealous.

His marriage, he realized he was going to be dumped by his wife.

The prosecutor asserted that the marriage was in free fall at the time of her death.

Autumn believed her husband had emotionally checked out, especially when it came to the issue of having another child.

She more or less told her cousin Sharon he was a cold fish.

Wow.

That just describes acres of sadness, doesn't it?

Yeah.

The prosecutor showed an email Autumn had sent her husband in the months before her death.

She wrote, I realize now I have been alone in this entire emotional journey.

I can't even speak to you without getting angry.

Did she ever say, Sharon, I'm going to leave him?

This isn't working?

And he was positively rattled to the core, said the prosecutor, when he found out Autumn was texting and emailing a male colleague she'd spent time with at a conference in San Francisco.

Bob Ferranti, said the prosecutor, suspected his wife was having an affair.

Autumn's cousin was certain that wasn't true.

So you don't think anything physical was happening, certainly?

But as the prosecutors told it, the defendant believed otherwise.

Rather than shoring up a crumbling marriage, the embittered scientist, his wife, the new rising star, came up with a cold-blooded solution.