It's against the law (right or wrong...Michigan or otherwsie) to electrify a fence with anything except the low-voltage, pulsing cattle type of electrical device... believe me: Being in the business for over 4 decades...I know. As cool of an idea as it may seem, those "crooks" could have owned a great deal of what your friend owns legally, after court let out.
I have locked up a lot of barns, after a lot of horses have gotten out. Dogs are a good deterrant but kids, gangs, etc....whatever David's neighborhood is dealing with, poison or shoot a good many. To say that alarms will not work if you're in an area with poor response or poorly timed response simply goes against all of the truth and facts with regards to alarms. The bottom line is still that: "If they have the choice to hit you or the guy down the street without the alarm system, they will hit the other guy all the time". If you are dealing with some folks on a vendetta against you, you are playing with a different set of rules...but you "probably" have a pretty good idea of who's hitting you.
Best, Capt. Chris