I had something similar that I used a wireless IR camera transmitting to a receiver hooked up to the DVR. The wireless camera was a loaner from a friend, and was effectively crap. I was eating 9V batteries every 6 hours. I finally had to snake an extension cord out 120' for constant power. That's how I got a positive ID on the guy. Now that I have a good system, If I had to deal with it again, I'd invest in a better transmitter/receiver unit that uses any camera. I have four good cameras already. Positioning camera's is the key (that, & they need to be good cameras).
The reason the DVR is so slick is that the software they use nowadays makes finding events recorded on the drive easy, and you can manage the memory well, and it networks into a PC. All this stuff is little pricey, but the right equipment will catch the guy in short order. If you're planning to use it to prosecute someone, there's a legal standard that needs to be incorporated into the equipment so the encrypted video can't be photo-shopped. A good lawyer would argue that point. The cheap stuff at Costco or Home Depot is ok for catching a babysitter or something, but anything outdoors will require a little investment.
A decent game camera might be a better choice if it gets the job done. It just depends on how many triggering events you have to sort through. It wouldn't have worked for me. My guy was too random, and there was too much non-target traffic I had to sort through to catch him.