Kentucky grave robber dug up Native American burial sites. Now he's headed to prison.

A Kentucky man described as a grave robber who plundered Native American burial sites has been sentenced to 15 months in federal prison.

Authorities started investigating Gary Womack, 60, of Simpson County after another man said Womack mentioned having a vault in his house with skeletons in it.

Police didn’t find any skeletons at his house during a raid, but the investigation showed he dealt in artifacts, such as arrowheads, removed from Native American grave sites in caves and rock shelters in south-central Kentucky, and from burial sites in other states, according to a news release and court records.

Womack told an undercover agent that he once dug up a Native American grave near the Mississippi River and found a skull, but it disintegrated when he picked it up, according to a sentencing memorandum from Assistant U.S. Attorney Randy Ream.

Womack also told the agent he dug up the headless skeleton of a woman, and that on another occasion the bones of an infant fell apart when he pulled them from a grave, according to the memo.

“In fact, he is a grave robber who talked for hours to the agent about digging into graves and collecting high grade relics buried with the dead,” Ream said in the memorandum.

The investigation started after a witness reported Womack had invited him to look at artifacts he had allegedly taken from Mammoth Cave National Park and other spots.

The National Park Service ultimately began an investigation in which an undercover agent posing as a California man who sold and traded Native American artifacts met with Womack several times.

Womack sold the agent artifacts from a mound in Posey County, Ind. Several people were prosecuted in the early 1990s after digging into the mound.

Artifacts from the site were supposed to have been reburied, but Womack was able to buy items from the site as recently as 2015, according to a news release.

Womack pleaded guilty to three felony violations of a federal law designed to protect archeological resources. The FBI assisted in the investigation.

The charges also involved artifacts from public land in California, Arizona and New Mexico.

When he sentenced Womack Monday, U.S. District Judge Greg N. Stivers said he was disturbed that Womack had dug into the graves of the ancestors of Native Americans for profit knowing full well it was illegal, according to a news release.

Ben Barnes, second chief of the Shawnee Tribe in Miami, Ok., urged Stivers in a letter to impose a sentence that would deter people from desecrating graves.

“The remains that are within the soils of our original homelands contains the hallowed remains of human beings, our ancestors,” Barnes said, according to the U.S. Attorney’s Office.

Police recovered all the artifacts involved in the case, which will be returned to tribes.