Everyone has to make their own decisions, ones that they can live with. However, I feel some obligation to point out that there may be legal consequences. Goldstar has summarized when a citizen may generally use deadly force and not be charged.
While there are circumstances where a fleeing person is such a danger to innocent people that it is justifiable for a citizen to stop them with any means, those are pretty rare.
Most of the time when the offender no longer is threatening or capable of threatening the life or limb of you or a person you know, then law say its no longer self defense. It will first be up to the prosecutor to decide whether any reasonable person would have done the same. If he or she decides no, then it will go to a jury to hear the case and decide.
If anyone is interested in this topic, I will second a post made in another thread that Massad Ayoob's classes are invaluable. A lot of his advise is available from his books, magazine articles and in recent years, youtube video. I'm not LE, but first heard about Massad Ayoob from LE coworkers long before the internet. This is just to say he is not an recent self-proclaimed expert. Rather he is a long respected former police officer and trainer who has been accepted as an expert witness by courts in many many cases.