A 17-year-old boy who disappeared last year was killed during an argument with a friend and then buried at a cemetery, concealed in a woman's freshly dug grave, authorities said.

Richard Waive Palmer (search), 26, was being held in a Maricopa County jail Monday on a charge of second-degree murder. He confessed last week to killing Robert K. Martin (search) in April 2004 by hitting him over the head with a baseball bat during an argument, authorities said.

Investigators exhumed the body last week. Authorities still need to compare dental records to make a positive identification.

"Had this guy kept his mouth shut, we would've never, ever found out what happened to this victim," Detective Tony Morales said.

Authorities learned that Martin, of Naperville, Ill., went to Phoenix to see Palmer and to buy marijuana for resale in Chicago, where the drug's street value is higher, Morales said.

Palmer told police he killed Martin, then put the body in the back of an enclosed truck and later in a rented storage facility, Detective Jan Butcher said.

Late one night in May 2004, Palmer took the body to Resthaven Park Cemetery, and found a freshly dug grave. He shoveled about 4 feet into the ground, and put Martin's body in the hole, near the top of a woman's coffin, authorities said.

Detectives had originally suspected Palmer, but had no evidence of a crime. They questioned Palmer again last week after a private detective hired by Martin's family told authorities he had made incriminating statements during an interview.