Years ago I clipped this prayer out of a collection of prayers to St. Michael. I keep it near my desk and pray it often.
"Please protect us, St. Michael the Archangel, against violence, murder and robbery. In your goodness preserve us today from all the malice of sinful and wicked men. In your sleepless vigilance watch over the safety and welfare of our homes, and keep guard over our possessions. Ever hold in your special care, most triumphant St. Michael, the forces of public order against the crimes of evil men, and defend all honest citizens in time of peril. We ask this of you through Christ, our Lord. Amen."