Updated

An 11-year-old boy shot his father's pregnant girlfriend in the back of the head while she was lying in bed in their western Pennsylvania farmhouse, then got on the school bus and went to school, authorities said Saturday.

Jordan Brown was charged Saturday as an adult in the shooting death of 26-year-old Kenzie Marie Houk, who was 8 months pregnant, Lawrence County District Attorney John Bongivengo said at a news conference.

Houk's family and friends, who gathered at her parents' house Saturday night, told The Associated Press that Houk had experienced problems with the boy in the past.

"There was an issue with jealousy. He told my son stuff," said Houk's brother-in-law, Jason Kraner, 34. "He actually told my son that he wanted to do that to her."

Brown, the son of Houk's live-in boyfriend, was charged with criminal homicide and criminal homicide of an unborn child, Bongivengo said. He was being held in Lawrence County Jail. A preliminary hearing is set for Thursday.

The fifth-grader was picked up from school Friday by Pennsylvania State Police, who found Houk's body after her 4-year-old daughter told tree cutters on the property that she thought her mother was dead, Bongivengo said.

The murder follows another shocking killing linked to a boy. On Thursday, a 9-year-old Arizona boy reached a plea deal with authorities who accused him of the fatal shootings of his father and his father's roommate. The boy pleaded guilty to negligent homicide in the death of his father's roommate while the murder charge in his father's death was dropped.

On Saturday, the Pennsylvania boy told police there was a suspicious black truck on the property that morning, causing investigators to look into a false lead for about five hours, he said.

Inconsistencies in Brown's description of the vehicle led police to re-interview the victim's 7-year-old daughter, who implicated the boy in the killing, Bongivengo said.

"She didn't actually eyewitness the shooting. She saw him with what she believed to be a shotgun and heard a loud bang," Bongivengo said, adding that the weapon, a youth model 20-gauge shotgun, was found in what police believed was the boy's bedroom.

The shotgun, which apparently belonged to Brown, is designed for children and such weapons do not have to be registered, Bongivengo said.

Brown's attorney, Dennis Elisco, said the evidence points to the gunshot wound being "consistent" with the boy's hunting gun, but he wanted to see stronger proof that it was Brown's.

"I believe Jordan did not do this and I'm looking forward to seeing the physical evidence to see if it matches with what I think happened," he said Saturday after meeting with the boy in jail.

The attorney also said he met with the boy's father, Christopher Brown, and planned to file a motion Monday to have the boy released on bail and move the case to juvenile court.

The attorney said Christopher Brown was "in a state of actual shock and disbelief." There was no indication the boy had a problem with Houk, he added.

"This is a tragic, extremely tragic situation, and it's way too early to have any substantive comment," Elisco said.

Police said they had no motive for the shooting, and Bongivengo would not say whether the boy confessed.

"An 11-year-old kid — what would give him the motive to shoot someone?" Houk's father, Jack, told the AP. "Maybe he was just jealous of my daughter and the baby and thought he would be overpowered."

Jack Houk said the family had gathered at his home in nearby New Castle on Thursday night to celebrate his 4-year-old granddaughter's birthday. Everyone was excited about the pending birth of his daughter's baby, he said.

"That's the last time I seen her, my daughter," Jack Houk said.

He said Brown was raised by his father and grandmother. Houk and the boy's father had been together since May 2008 and were engaged at Christmas, her father said.

Jack Houk said the boy and his father used to practice shooting behind their farmhouse, and the two enjoyed hunting together.

He didn't know of any recent problems between the boy and his daughter, but said there had been "some tension" in the beginning. Houk said his daughter had been working hard to forge a relationship with the boy.

Kraner, Houk's brother-in-law, said Jordan could be a "rough kid." He said his son was interviewed by police about the boy.

Kenzie Houk had been renting the farmhouse in Wampum, a rural community northwest of Pittsburgh, for no more than a year, neighbor Cameron Tucker said.

Tucker's wife sometimes drove Houk's younger daughter to the bus stop because she went to preschool with the Tuckers' 5-year-old.

"She was very protective of her kids," he said.