No need to apologize. The best even I could do was indirect reasoning.

...Sorry, Ringo. I really don't know.

The problem with this case is that the evidence we have for any conclusion is almost entirely psychologically based.

We have almost no physical evidence to speak of.

But I don't think psychological contradictions are any less important than physical ones.

Contradictions?

First off: Why did they stay on the phone for so long?

"I'm sure it is. I'm really not used to hot places like that. Are the kappa really okay with it?"

And despite that, they were calm from beginning to end. They were even the one to start chatting about the heat for no reason.

Even if they'd locked the boiler room exit, they had no idea where a pursuer could come from.

The culprit's phone call to the custodian's office went on for more than a minute. That's way too long for someone who just committed a murder and is trying to escape.

Yes. Questions about the killer's psychology.