Timber theft in Missouri is not on the rise, if anything there is less than in the past.  But it does occur.  The most usual manner is a perfect fit for the situation you describe.  The loggers will take a few trees along the property line, usually the best, expecting that the landowner either won't find out until they are long gone or they can pay a minimal amount to settle.  Usually $1,000.00 is offered, then if not accepted, they will stall, not answering phone calls and making excuses, until, again, the job is done and they are gone.  They are practically daring the victim to take them to court.  It's very costly and time consuming.  Missouri has no public agency to assist in timber theft.  There is technically some assistance through the Missouri Department of Conservation for Forest Crop Land owners, but it has been little used, and the program is being eliminated by atrophy.  For a brief period of years the state code extended this protection to all landowners, but when it was pointed out to the Department, the state code was changed back to withdraw the protection.  Your only recourse is to hire an attorney, and a forester, and take your chances in court.