An 11-year-old boy missing since last week was found slain early Monday on a golf course near his home, and a twice-convicted child sex offender was arrested in his death, police said.

An autopsy was being performed on the body of Irvin Harris to establish the cause of death.

"The body had suffered a level of decomposition," said Detective Donny Moses, a police spokesman. "Everything points to the fact that he was actually killed on Friday."

Melvin Jones Jr., 52, was arrested Monday afternoon inside a downtown fast food restaurant after police got an anonymous tip that he was there. Police planned to charge him with murder, Moses said.

Jones had befriended the boy and was last seen with him, investigators said.

Jones pleaded guilty to child sexual abuse in 1989 and served about seven months in prison, said Joseph Sviatko, a spokesman for the Baltimore state's attorney's office. He pleaded guilty in 2002 to a sex offense involving a 15-year-old boy and was sentenced a year in prison, Sviatko said.

Jones registered as a sex offender after his 2002 conviction and was on probation, Sviatko said.

Irvin was last seen by his family Friday around noon, when he left for his summer job at a nearby grocery store, Moses said. His body was found before daybreak in a densely wooded section of the Clifton Park Golf Course, out of the sight of golfers.