A Bullet Runs Through It (Part 1) - S6-E7
Other mistake: "A Bullet Runs Through It," part 1; while Catherine is in the lab reviewing the audio tape of the police call to dispatch, the dispatcher claims that the first call she received was at 6:34. First, her lips do not match what she is saying and then when they show the screen with the audio playing, the screen reads "first call 5:43."
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.