Assistance in the passage (60-80 days) (This Is the Police)

Question # 1
At first I could investigate the Dentist case, but even then I thought about it (for a couple of game days, without delving into the messages). And now there is no opportunity to participate in the case. I can only send detectives to another murder and that's it. I read it on the forum, they write something about the "rat" (maybe =) I don't remember =)). As a result, will I be able to catch him or will I have to survive the remainder without a caught dentist.

Question # 2
Is it worth starting an investigation against Christopher G. Sand himself (Lulei will not hang out ahead of time?)

I am waiting for your help. The game is amazing!