A Kentucky man described as a grave robber who plundered Native American burial sites will serve time in prison.

Gary Womack, 60, of Woodburn, was sentenced to 15 months in federal prison on Wednesday for violating a federal law that protects archaeological remains.

Womack pleaded guilty to three felony violations of the federal Archaeological Resources Protection Act (ARPA) in March, including trafficking in archaeological resources (Native American artifacts) from the western United States.

According to the Glasgow Daily Times, the case resulted from a three-year undercover investigation by the National Park Service, based upon allegations that Womack possessed human remains which originated from Mammoth Cave National Park.

A federal agent posed as someone interested in ancient artifact collections during meetings at Womack’s residence.

The investigation revealed Womack’s dealings in artifacts removed from the graves of Native Americans buried in caves and rock shelters in southcentral Kentucky and also burials from Ohio and Mississippi Rivers.

WKMS reports, Womack sold the undercover agent artifacts from a mound in Posey County, Indiana. Several people were prosecuted there in 1992 after digging into the mound. But prosecutors said Womack was able to purchase the artifacts as recently as 2015 in Warrick County, Indiana.

In sentencing, Judge Greg N. Stivers told Womack that he was disturbed the defendant had chosen to dig the graves of the ancestors of Native Americans for profit and had done so while being fully aware of the laws he had chosen to violate.

A letter from Ben Barnes, Second Chief of the Shawnee Tribe, of Miami, Oklahoma, was made a part of the record and read at the sentencing hearing.

The letter said, in part: “The remains that are within the soils of our original homelands contains the hallowed remains of human beings, our ancestors. We would urge the court to send a message to all those what would desecrate a grave, that ARPA violators will be prosecuted to the fullest extent of the law.”

All artifacts in the case have been recovered and will be repatriated to tribes.