The Buchanan County Prosecuting Attorney filed first-degree murder charges Wednesday against 16-year-old Joseph Sean Johnson, just hours after the teenager was certified for trial as an adult.

In a news release, officials announced that Mr Johnson was charged with two counts of first-degree murder, or in the alternative second degree murder.

The charges stem from the fatal shooting of James and Beverly Johnson, the defendant’s grandparents with whom he lived. The pair were found at their home in eastern Buchanan County July 3.

In court documents officials say the suspect was stopped in Platte County for invalid plates displayed on his grandfather’s car. According to the affidavit, officials learned the suspect told an acquaintance on the phone he believed he had murdered his grandparents. Both were subsequently found fatally shot at their home at 8610 Hurlingen Road.

A judge set bond at $250,000 pending Mr Johnson’s first court appearance August 14. The defendant is in custody in the Buchanan County Jail.

Detective Shawn Collie of the Buchanan County Sheriff’s Office said in a court affidavit he didn’t believe Mr Johnson would show up for court because he is a minor and is now homeless.

In the court affidavit, Lieutenant Collie said the defendant had approximately $600 on him, along with extra clothes, and a credit card belonging to his grandparents, and was carrying directions to Louisville Kentucky with him when he was arrested. He was just 30 to 40 minutes away from the crime scene when he was stopped.

Prosecutor Dwight Scroggins says the first degree murder charges each carrie a penalty of life imprisonment without parole. Murder in the second degree carries a penalty of 10-30 years in prison or life without the possibility of parole until 85% of any sentence has been served.

Earlier Wednesday, Circuit Judge Dan Kellogg certified Mr Johnson for trial as an adult.