A Simpson County man who admitted illegally acquiring and trading prehistoric artifacts taken from public land was sentenced Monday to 15 months in prison.

Gary Womack, 60, of Woodburn, was sentenced in U.S. District Court after pleading guilty to three counts of violating the federal Archaeological Resources Protection Act.

Womack reached an agreement with prosecutors that included the recommended 15-month incarceration. He will be allowed to surrender at a later date.

The law forbids the purchase, sale, exchange or transport of any archaeological resources that have been removed, sold, bought, exchanged, transported or received in violation of state or local laws.

Federal prosecutors alleged Womack violated the law by acquiring artifacts that had been illegally removed from a Native American burial mound in Indiana and engaging in illegal trade to receive blades and ceramic vessels removed from federally protected lands in Indiana, Arizona and New Mexico.

An undercover National Park Service agent visited Womack’s residence multiple times and recorded conversations in which Womack mentioned he was aware that some artifacts in his collection came from federally protected sites and could not legally be sold at artifact showcases.

Womack also cited during conversations with the agent other criminal cases involving the removal of artifacts from protected sites, according to court records.

“I do view this as a serious crime,” U.S. District Judge Greg Stivers said at Womack’s sentencing. “I’m most impacted by Mr. Womack’s comments that he was aware of the illegality of this behavior. The fact that he continued to engage in this kind of commerce really shows a disrespect for the law.”

Authorities were made aware of Womack in 2012 when a man who had been invited to his house contacted the Kentucky Heritage Council to report that Womack was in possession of potentially illegal Native American artifacts collected from Mammoth Cave National Park and other locations.

The man alleged he had been shown a walk-in vault in Womack’s basement that featured skeletons, though no human remains were found when law enforcement executed a search warrant in 2016, federal court records show.

The tip was passed along to a park ranger at Mammoth Cave, who relayed the information to a National Park Service special agent based in California.

The agent’s investigation involved posing as someone interested in ancient artifact collections during meetings at Womack’s residence.

During one visit in 2014, Womack arranged a transaction with a third party who offered to sell blades removed from a protected burial mound in Indiana, and the agent agreed to pay $1,250 for a portion of the artifacts, court records show.

In a later exchange, the agent sent Womack photos of stone artifacts from protected lands, and Womack replied that he was “in the market” for pottery and discussed meeting at artifact shows.

The pictures were of artifacts collected as evidence in prior investigations into illegal trading, according to court records.

During the sentencing, Assistant U.S. Attorney Randy Ream read a letter from Ben Barnes, 2nd Chief of the Shawnee Tribe, in which Barnes urged Stivers to uphold the plea agreement and sentence Womack to prison.

Womack declined to make a statement at the hearing.