Best option I think would be I think the police chief... playing the concerned teacher, asking after a missing student he was supposed to have a conference with Friday or Monday who didn't show and whose parents don't know where he is? He might not get close to the chief, but sniffing around the office might at least give him an idea whether he should try harder, and it's the first plan that would come to him. I will think further if that doesn't work as a stepping stone at least.

ETA: Whoops look at me not even reading the whole plot post. I try to reply too fast and miss shit XD Nevermind on the missing student deal, given the news. Maybe he could come in instead with a made-up lead about arson at the house?

And if you think the four-character plotline would work using Lyall and his students, let me know and I'll contact said students and see if they're interested ^^