Deborah Roberts

And instead of referring to Emma by her name, he keeps calling her the girl.

If that's your girlfriend of two years who you're in love with, who you're posting these heartbreaking tributes to on social media, why aren't you using her name?

Riley tells them he'd been trying to speak with Emma all weekend, but she wouldn't engage, that she even blocked his number.

Riley offers police his alibi, saying after Emma hangs up on him, he goes to his grandparents' house, then drives back to his dorm where he breaks down in the parking lot.

I just sat there for about two to three hours and just wept, just looking at pictures of us and stuff like that.

He was really, really upset about this, but when you saw him, was he broken up?

He did not have the gun, didn't know where the gun was, and basically didn't have anything to do with it.

No, you had already talked to friends of his who had told you that he had this gun.

Yes, ma'am.

What if I told you someone told us that they saw you with a gun?

I knew immediately within minutes of sitting down to talk to him, Riley Gall wasn't going to confess to anything.

He wasn't going to do it.

Detectives then turn up the heat, pressing Riley about an odd question he had for his friend Noah.

How to get fingerprints off a gun?

It's more like a horn.

It was, yeah, Abel would be putting it mildly.

Everything about the interview, his answers, his body language, it's screaming that he's got something to do with this, that he's involved in some form or fashion.

Riley Gall has gone from person of interest to suspect in the death of Emma Walker.

I do want to thank you for coming in and talking to us.

I do appreciate it.