The death possibilities he thought and/or she thought ended when JN was in a chokehold, all passengers exited the car and 2 other men where helping DP hold down JN.Sounds like lots of people on the train thought JN was going to kill someone, and DP intervened- no one knew if he had a weapon or was going to kill that day… are you suggesting that DP should have waited to see if JN actually killed anyone before stepping in?
With no possibility of JN killing anyone DP went on to strangle JN to death,\.