My car was totaled out

My car was totaled out while paked in front of my house. It was at 4:00 am. No one was in the car. All were in bed asleep. The Police woke me up. I went outside where I was met by a neighbor who lives in the next block over. He said his car was stolen from in front of his house. He had left it running while he went in the house to get his billfold. He came out and saw two men get in the car and leave. He went back in the house, got his wife and pursued his car . The car crashed into mine 3 blocks away. He said he saw the crash and got out of his vehicle and chased them on foot but could not catch them. He then went back home and called the police.
His insurance has denied my claim saying they have no responsibility because the car was stolen
My position with his insurance company has been that since he left the keys in the car and the car running and then chased the thieves causing them to drive more recklessly than they otherwise might have that he should be responsible at least to some degree.
If he had not left the car running it wouldn't have been stolen. If he had not chased the car it wouldn't have hit mine and I wouldn't be without a vehicle. My car is old and had liability only.
I live in Missouri which is a Comparitive Liability State. In otherwords you assign degrees of responsibility to each party.
Does anyone know about similar cases like this where compensation has been paid. Does anyone know what the law says about this situation? I appriciate anything you might know or a site where I could research this particular topic.

Thanks, Phil