Revealing mistake: Ribbons is talking to Grissom and Nick in the autopsy room, and the latest post autopsy female lies on the table. Grissom says, "He choked her unconscious, and brought her..." and when the shot faces her head and shoulders, watch her neck - you can see the veins in her neck pumping. (00:06:45)
Continuity mistake: When Grissom first arrives at his own home, he turns on his stereo and adjusts one of the levels. In one shot, he uses his left index finger to push it up, but in the next, he is moving it with his right index finger and thumb.
Answer: He doesn't have the authority to arrest him - when anyone is arrested in the show, a police officer does it. Also he tells Ty that he is going to be submitting his case findings to Ty's insurance company, who would no doubt contact the IRS, who then would have him arrested for fraud etc.