AP

JASPER (AP) — A 14-year-old boy was charged as an adult Tuesday in the fatal shooting of his 12-year-old sister outside their rural southwest Missouri home.

Jasper County prosecuting attorney Dean Dankelson said the second-degree murder, armed criminal action and first-degree attempted arson charges filed against Thomas "Tristan" Potts are identical to the juvenile charges he faced previously. He was being transferred Tuesday from juvenile to adult custody.

Potts was 13 in October when Teresa Potts was killed. Dankelson said the brother and sister had been adopted out of foster care. He said he wasn't aware of any other foster children living in the home.

The boy's attorneys, Wes Barnum and Keith Pennick, didn't immediately return a phone message from The Associated Press seeking comment. Dankelson said the teen's arraignment could be as early as Thursday morning.

The new charges were filed one day after a juvenile hearing ended with a judge ruling that the teen could be tried as an adult. The Joplin Globe reports that responding deputies found the girl mortally wounded. She had gunshot wounds to her temple and right shoulder, Chris Carriger, a detective with the Jasper County Sheriff's Department, testified at the hearing.

Tristan fled into some woods after the shooting and turned up later near a shop building behind the house, close to where investigators eventually recovered two handguns. Carriger said the teen tested positive for gunshot residue on his hands.

The detective said that when he entered the house, he found the home in "messy disarray," with black gunpowder strewn throughout the rooms and about 500 rounds of .22-caliber bullets in two skillets in the kitchen.

Carriger testified that the investigation turned up three lists that bore the fingerprints of Tristan Potts, including one titled "Supplies for Georgia." Investigators later learned that the boy had been in contact on Facebook with a female in Georgia. Items on the to-do-lists, including a gun and food, were found near the home's front door.

If convicted as an adult, Tristan could receive both treatment and training through a special program until he turns 21. He then could be transferred to an adult prison if the court determines he should remain in custody, said Belinda Elliston, attorney for the Jasper County juvenile office. She said he would have to be released when he turns 18 if he is tried as a juvenile.