Wow Sal!
Where did it happen? Maybe there are cameras around that area you can get from? Gas Stations? Bank ATMs?
As BD said either the person was drunk or he was uninsured or even worse BOTH!
I think you should take the lady with the whiplash to hospital just in case. One of my aunt's car got rear ended on a RED light by a stupid drunk and she had taken off the seatbelt a few sec to give something to the kids in the back seat. She went through the windshield. She's fine now but gets pain once in a while in her back. Went through lot of therapy. Kids are fine too.
Turned out the driver was an illegal from S America with suspended driving license. Her car hit the car in front of her and the stupid guy sued my aunt for it!!! The case got dismissed but the nerve of that guy!