Factual error: The CSI staff repeatedly refer to the murder weapon as a tire iron. It is a crow bar or demolition bar. It had a nail pulling head, not a socket for the lug nuts.
Factual error: When Captain Brass is in the travel agency and talking to the woman who works there, they access the last bookings taken by the victim. 4 lines up from the bottom, "Bob R" seems to have booked a return trip to Paris in Germany, when in fact Paris is in France.
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.