Brian's suspicions that the inspector's visit was more than just a courtesy, and why, was spot on. Any person of interest is always a possible suspect in some manner or other. The fact that the official investigation was initiated by their private investigator going to the police, may or may not lead to the information that it was they who employed the service.
Toby was a good judge of character regarding Jasper and that he brought his concerns to his dads was fortunate and mature.
Toby's mom, to be charitable, is out of her depths in several ways including being a parent.