Hey David ...
can a Gammo puncture a tire ... or two?

The CAPT is right "on target" with his advice. How many times have you heard about someone getting their security system AFTER getting robbed?
Two years before my US Army retirement, we moved from Ft Knox to Elizabethtown, KY, a relatively, quiet low-crime area. Right away, I contacted a local, security company. Not ADT, not Brinks, or any of those commercial, out-of-town outfits! Just like CAPT Chris said, I had installed a complete security system with wireless capability to my detached garage, all windows/doors protected, etc, AND WITH LIVE, "REAL PERSON" MONITORING SERVICE. It is fairly low cost, $66/quarter and I own the complete hardware system. We get 20% off our homeowners insurance too! The insurance discount has more than paid for the system over the last 15 years. Oh yeah, I have a dog, Kimbers, Smith & Wessons, Randalls, etc but the security system is the real "rattlesnake in the grass" for those who intend to be criminals. Get one now if you own a home, don't wait to be a victim.

In the "old days" the systems I was speaking of would have ran well over 2 grand. Nowadays, with electronic technology so advanced and labor relatively cheap (and not as many hours of it required to install the new stuff) the whole shootin' match would run a lot less.
Every little "extra" or backup you can add will help. Also:...and this is "KEY"...Most crooks, even the stupid kids, will hit the house (car) that doesn't have the security system, not the ones that "do".
Best, Capt. Chris

UPDATE : I saw my neighbor in the supermarket last night. He said at least three other homes in the neighborhood had their cars burglarized the same way in November. So, it is safe to say we have a problem that I was not aware of, and it is an ongoing problem.

The house has an internal security system, but the external system is limited to multiple spot lights and a large dog who has gotten fat and lazy over the winter. The whole system needs to be beefed up, especially since the likelihood of a return visit seems inevitable.

You would have to be incredibly stupid to enter my home uninvited, especially at night. Whoever did so would be asking for an unpleasant evening.

They're "burglars" David. Many of them "are" incredibly stupid!
Best, Capt. Chris

I have found that the right dog trained correctly can be quite a deterrent within a fenced area for more menial thieves, the kind that break into your car or steal things out of your yard. Lights bells or whistles will be a waste if you are not in an area where they will attract attention. Sometimes the most direct and simplistic approach can work the best.

Reminds me of a guy I used to work with. He had people doing much the same including peeking in their windows at night. So he took a buch of pieces of 1x's and drove drywall screws through them and set them down, point up, under his groundfloor windows.. His yard was fenced too, so he wired up a motion detector to a contactor which in turn electrified his fence with 220VAC and turned on several large high powered lights on poles. He then put 'No Trespassing' signs up at his property perimeter.

A few nights later his perimeter lights came on and he heard screaming, and the morning after he left the motion light off he found a spots of blood under his windows and a couple of the screwed boards were gone. Needless to say he got a visit from the local police. When they saw his 'NT' signs, they left him alone. In that state, 'NT' means no one is legally allowed to trespass.

True story. Happened in West Michigan near Paw Paw back in the mid 90's.

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

Legal or illegal, its funny the police never made him shut it down or pushed the issue. Oh well....

As to the other points, I have gone the dog/fenced area route in both a neighborhood setting and in a very rural area. Based on what the op said (no mention of kids, etc iirc) this could be much more cost effective, imho. But like I said, it takes training. Ultimately a system is the final line of defense. But they are riddled with their own set of issues depending on the system. So nothing in the way of protection is fool proof. Like another poster said, its always best to take away their lures-keep all your toys and valuables out of vehicles left parked outside. But to each his own. All I know is what has always worked for me, and this is the first residence (in 35 yrs) we have owned with an alarm system in it (central alarm), and the only reason we have it is because it was here when we bought the house.

David,

Really sorry to hear about this and think the monitor camera that can record digital images on a computer is the way to catch anyone red-handed.

It seems like burglaries are on the rise in many places because of economic hard times. Could be that is what you are experiencing. No excuse for illegal actions of these douchers, but possibly a cause for thinking things will get better when economic conditions improve.

Unfortunately, I believe any form of booby trap is illegal. Too many criminal rights.