Left turn is always at fault, this is compounded by the illegal lane change... the only possible way they can say it was your fault is the speed issue - but with no police report, and apparently no witnesses, it's up to the insurance companies - they'll go through abrogation, which means the legal eagles on each end will haggle until one admits "Yeah, we'll cover it." Since he was making a left turn, you had right of way, and they can't prove you were speeding since he had no damage and no witnesses, you seem to be in the clear. Your insurance should win this one easily, if you told the story well... I'm assuming you hit somewhere on his rear panel, and not straight-on in the back - that gets trickier. Here in Maryland, the rear-ender is always always at fault, no matter why. But if he was still in the middle of the turning procedure, you're ok.