He also lied to the police when they arrived, saying that things were fine between him and Terri (they weren't). He even tried to plant an explanation of suicide by telling the cops he didn't know any reason she'd be suicidal. That bit of hocus-pocus should have set off the alarms, but it didn't.
I find your scenario entirely plausible. Unfortunately, I also don't see much hope of the crime ever being thoroughly investigated and justice being done.