Two men entered guilty pleas this week to violating Virginia’s hunting laws by baiting black bears for hunters.

Randy Butler and Thomas Neal Marks were at the center of a three-year investigation that uncovered criminal activity spanning a decade. The men sold hunters the opportunity for a “guaranteed” bear hunt for $3,000 — in other words, the customer could keep coming back until he killed a bear.

Butler and Marks were able to make the guarantee, because they were attracting bears to a parcel of land they leased by using doughnuts, dog food, crabs, fish and deer carcasses.

Butler owned and operated a company called Virginia Guide Service, for which Marks worked as an employee.

The company leased land in Suffolk just across U.S. Route 58 from the Great Dismal Swamp, where bears are known to live. They also maintained a hunting lodge there, known was the Magnolia Lodge.

The company advertised its services at outdoor shows up and down the East Coast, selling the guaranteed bear hunts, as well as deer and turkey hunts. Hunters who killed deer were encouraged to gut the animals and leave the remains near the hunting stand to attract bears.

The investigation began in 2007, when a special agent with the Virginia Department of Game and Inland Fisheries went undercover to expose the illegal practices of the business.

He went to a hunting show in Harrisburg, Pa., in February 2007 and set up a hunt for November. The special agent recorded phone conversations with Marks that included references to baiting, and he witnessed the baiting practices.

Butler pleaded guilty to two counts of instigating others to trespass and three counts of hunt over bait to take a wild animal. Marks pleaded guilty to three counts of hunt over bait to take a wild animal.