Normally insurance follows a vehicle first and driver second so if your brother plans on making a claim for the damages to his vehicle it would need to be through his own insurance company.

Since the driver was "drifting" your brother would need to read through his policy and speak with his agent to find out if damages resulting from this careless act would be covered under his physical damage coverages of collision or comprehensive.

Many insurance claims involve drivers doing stupid things. Depending on the circumstance a claim could be denied. For example, whenever a person making a claim is charged with committing a felony, most companies will withhold benefits until the trial and/or prosecution has completed the trial.

If your brother decides to instead go after the friend personally for the costs of the repairs and the friend does not willingly pay he may need to take him to court. If he does so then having the off duty detective as a witness would be helpful to his case.