fleeing the scene of an accident is a very serious crime.
He claims he was only going 45, police claim 70. Ok, it can be proven in court which was the fact. If he was indeed going 70, it's clearly his fault and not just "an accident."
Also, I don't know the speed limit in that particular place that he was. Even if it was 30 and he was going 45 as he claims, he's still at fault.