Infrared game camera set up over the gate/lock? Is photographic evidence of this nature admissible in court?
The admissibility of photographic evidence would probably depend on the judge hearing the case. I would think that most judges would welcome photographs and video.
Have you contacted your conservation officer? If not, give him or her a call and advise them that you have a recurring problem and signs and locked gates haven't been effective.
If you find somebody on the property get all of the information you can get, such as vehicle descriptions, license numbers, and any personal info that's easily obtained. Call the CO as soon as possible, give them the information, and be available to go to court and testify and assist in the prosecution in any way you can.
There's a difference in folks that accidentally stray onto property with unmarked boundaries, and chronic trespassers that cut locks and fences.
Warnings don't work on the chronic offenders. They need to be dealt with by the court systems.