I am so sorry these crimes of opportunity keep happening. I would suggest asking one of our community officers to come by and give you a sight inspection. They can see things that most of us would not, things that are making your home more appealing to criminals. We have great officers who are more than willing to help anyway they can. We have talked to them before at our neighborhood watch meetings about this and I believe several neighbors have used them.
I have installed driveway alarms around my house which sound an alarm in the house if any comes into my yard, battery powered, and wireless. They are pretty cheap at harbor freight.
http://www.harborfreight.com/cpi/ctaf/Category.taf?CategoryID=770&pricetype
Here is an article I found online as well.
pmnwatch
Believe it or not, landscaping can be an important part of a good home security plan. A burglar who is 'casing the joint' from the street will choose the house with tall shrubs and trees that provide hiding places. Homes with little or no outdoor lighting are preferred targets as well.
So, how can you landscape to protect against burglars while still creating an aesthetically pleasing yard? Here are a few tips:
You don't need to eliminate trees, but keep them trimmed back from your house; tree branches can be used as a ladder if they are next to a window or skylight.
Mow your lawn regularly; an unkempt lawn can suggest to a thief that the owners are away on a trip.
Store ladders, lawn chairs, and picnic tables out of sight lest they be used as a means to reach high windows.
Trim back shrubs growing near doors and walkways, keeping them 3 feet or shorter in height. Also, don't allow shrubs to block any of your windows.
Adding gravel under windows makes for noisy footing for would-be thieves.
Consider planting thorny bushes (of the low growing variety) around windows. Some examples are: Hawthorne, Rose Shrub, and Barberry.
Forgo privacy and keep your trees and shrubs trimmed back in order to allow a clear view of the outside of your house. Having neighbors that can see your doors and windows can help deter thieves even if you happen to be out of town.
Keep your yard well lit. Motion-detecting lights make decent choices; body heat-triggered sensors are even better (less likely to be triggered by a waving branch or a passing animal).
Dogs are not a complete home security plan, but can make good home protectors because they have keener hearing than humans, along with a propensity for barking at strangers. Dogs training can help your dog learn exactly what you want him to do.
http://www.streetdirectory.com/travel_guide/4490/home_improvement/how_to_modify_your_landscaping_to_protect_your_house_from_burglars.html