if you fear for your own life or the life or your neighbors, I would say do what you can.

If things get serious, hold him at gunpoint, if he runs, let him run. Atleast you scared him off.

If he threatens your life, put that gun to good use and remember these words "I feared for my life".

Just act with integrity and honesty and everything will be fine. Don't be a vigilante, but if push comes to shove, be a man and protect the innocent.

Remember, there was a day when there were no police to protect you.

If you can't count on your neighbors and community, then really, what's the point?