When 9-year-old Katelynn Arnold didn't appear right away after one of her frequent bicycle rides along her rural Alabama road, her concerned aunt went to look for the girl.

The woman, who is the girl's foster mother, checked with a neighbor whose daughter often played with Katelynn, but he hadn't seen her. When she returned home Thursday evening, she found the girl hanged from a tree with an old tire swing rope, deliberately, authorities say, by her 14-year-old half-brother who was charged Friday with murder.

The cotton rope was tied in a simple knot around the girl's neck, but was not a hangman's noose, said St. Clair County Sheriff Terry Surles. County Coroner Dennis Russell said an autopsy found the cause of death was homicide due to ligature strangulation.

The neighbor, Ricky Campbell, could only shake his head when thinking about what happened.

"She never got a chance to grow up. Her life was taken away," he said.

The accused boy admitted to killing her by hanging, Surles said. He said the boy told investigators a motive but Surles did not release it. A call came into the sheriff's department about 8:10 p.m. Thursday and by the time investigators arrived, rescuers had removed the girl from the tree and she was pronounced dead at a hospital.

The half-siblings were living with their aunt and uncle in Ragland, a town of some 1,900 people about 40 miles northeast of Birmingham, as part of a foster home situation, Surles said. Authorities did not release their names, but Campbell identified them as Jerry and Teresa McMahan and an address search shows a couple by that name living on that road.

Campbell said the children have been staying with the couple for years and authorities had no information about their parents. It was not clear whether the state had placed the children in the care of the McMahans or if the parents had sent the pair to live there.

Several relatives who gathered at the small, white home declined to comment Friday. Yellow police tape was strung around a couple trees outside the home along a one-lane road and a small bicycle with pink handle bars was parked out front.

The boy faces juvenile charges and his name was not released. Authorities could later decide to charge him as an adult.

After the girl was found and taken to the hospital, the boy went to bed, Surles said. He was arrested between 2 and 3 a.m.

Teresa McMahan came to Campbell's house Thursday evening looking for the girl, Campbell said. She returned home and a few minutes later he heard the ambulances arrive.

Campbell said he never saw any real signs of trouble out of the accused boy.

"He'd run off and do crazy things, but I never believed he'd do something like that. It's a bad situation," Campbell said.