HOUSTON -- Three teenagers are accused by Houston police of digging up a grave, removing a skull and using it to smoke marijuana.

Houston police said Thursday 17-year-olds Kevin Wade Jones and Matthew Richard Gonzalez, and a 16-year-old, dug up the grave with shovels, removed the skull from the coffin and converted it into a "bong."

Jones and Gonzalez were arrested Wednesday night and have been charged with misdemeanor abuse of a corpse, officials said. The 16-year-old was referred to the Harris County juvenile justice system. Investigators said another person may be involved.

Houston police said they initially interviewed Jones about the use of a stolen debit card when Jones told them about the grave theft. Asked why Jones would volunteer such a story, Sgt. John Chomiak said, "We can only speculate and guess to what goes on in the criminal mind."

Gonzalez confirmed the story to investigators in a follow-up interview. Police were led to a heavily wooded site, where they found a knocked-over headstone and water-filled hole more than 4 feet deep. At the time, the muddy water prevented police from seeing if the coffin had been disturbed.

"They dug into this gravesite and that was enough to warrant the abuse of corpse charge," Chomiak said. "There has to be further investigation into the actual gravesite."

Police said they do not know where the skull is.

A man named Willie Simms was buried in the grave, according to court documents. Chomiak said that Simms' next-of-kin had not been notified.

Residents in the area knew of the cemetery's existence, it did not appear to be maintained. Preliminary reports indicated it was a 19th-century "veterans" cemetery, he said.

All of the teenagers live in Kingwood and are home-schooled, officials said.