Hit & Run Street Racer will not reveal insurance coverag

Right after our son moved from Tucson, Arizona, to Washington state he was rear-ended by a hit andamp; run street racer at 70-75 miles an hour. Both cars were totalled. The racer and two buddies jumped out of their car and fled the scene. Luckily, my son had only minor injuries. Since the accident, the police agencies are doing nothing but bouncing our son around from the Washington State Patrol to the Pierce County Sherff's to the Puyallup Police Department. (I am married to a retired police officer and expected much more from them than that.) My son can't even get the insurance information from the owner of the car that hit him. The owner won't answer his phone or answer the door at his residence. Is there any other way to find out if this car is insured?...and if so, who it is insured by? The owner of the car told the police the car was stolen. Right! There is NO stolen car report filed. At this point, this hit andamp; run driver, who could have seriously injured or even killed my son is getting away with it. I don't like this! Our son's insurance company took care of his medical bills through his uninsured motorist bodily injury coverage, but you can't get uninsured motorist coverage in Arizona (he still had his Arizona coverage), which would have covered his totalled car. I can't express how frustrating this whole situation is. The guy driving this car needs to be held responsible for his actions. Any kind of help or advice about ANY of this would be greatly appreciated.