A 17-year-old from Virginia was captured in North Carolina and charged with two counts of murder in the shooting deaths of his mother and 6-year-old brother inside their home at the weekend.
Levi Norwood was apprehended by police after being accused of shoplifting, authorities said.
The victims were identified as Jennifer Norwood, 34, and her son Wyatt. The Fauquier County Sheriff's Office said Jennifer Norwood's husband, Joshua Norwood, came home to find his wife and younger son dead of gunshot wounds.
Levi Norwood then shot and wounded his father, who escaped and called for help, officials said. The father was hospitalised and listed in stable condition, Sheriff Robert Mosier said.
Sheriff's deputies surrounded the home in the 12800 block of Elk Run Road, just east of Route 17, believing that Levi Norwood had barricaded himself inside. But when deputies entered the home, the teenager was gone, the sheriff's office said. Officials said he had not taken the family car.
Fauquier mobilised a massive manhunt, using drones, a helicopter, bloodhounds and officers from surrounding agencies, advising residents to shelter in place. But Norwood did not turn up.
Then yesterday, a Fauquier resident reported that his red 2007 Toyota Camry had been stolen overnight from a neighbourhood about 16km from the Norwood home. Mosier said bloodhounds that were tracking Norwood indicated that he had been in the area, and a lookout was broadcast for the Camry. But the car had been gone for hours, and investigators soon learned that Norwood had spoken to friends about possibly leaving the state.
Later employees at an unidentified business called police to report shoplifting. Sergeant James Hartman, spokesman for the sheriff's department, declined to identify the location of the arrest until Fauquier detectives had a chance to speak with the teen. The stolen Camry was found in the parking lot, Hartman said.
The sheriff's office said Saturday that it had not determined a motive or what type of weapon was used in the double homicide. Guns were stored in the home, but it had not been determined whether any of those guns were used or missing, Mosier said.
Fauquier Superintendent David Jeck said counsellors were being prepared at the county's schools to help students and staff. "This kind of tragedy is obviously not something that Fauquier County is accustomed to," Jeck said. "It's a really, really horrible situation."
Jeck and Mosier said they did not know whether Levi Norwood had any reported behavioural or health problems. The sheriff did not have information on whether deputies had previously been dispatched to the Norwood home. Hartman did not have information on the professions of the parents.
Court records show that Joshua Norwood had worked as a sales representative for a company in Manassas, which said he no longer worked there, and Jennifer Norwood was a licensed nurse's assistant, but records show her license had expired.
Jennifer Norwood's Facebook page features photos of her sons fishing, pictures of the US flag and news about school fundraisers.
Two friends said Levi Norwood had a girlfriend. Hartman said that the girlfriend had been located and interviewed and that she was not with Norwood.
Adam Moore, 17, a classmate of Norwood, said he saw Norwood in school on Friday, and "he definitely didn't seem sad or anything." He said Norwood enjoyed hunting, fishing and country music. His family had only recently moved to the house where the violence occurred, Moore said.
Roberto Hernandez, 17, said he met Norwood when they were both 8 years old. He described him as a "nice kid" who was "friendly to everyone" in primary school. But by intermediate, Norwood seemed angry, quiet and withdrawn.
Hernandez said that changed when high school rolled around and Norwood found a group of friends. He was happier and less angry. Last year, Norwood began dating a girl at their school, Hernandez said.
But this week, Hernandez said, after dyeing his hair purple, he seemed on edge.
"One of my friends touched his hair the other day - not, like, to bully him, but just because it was all purple and freshly dyed - and Levi got up and said, 'If you touch my hair again, I will dislocate your jaw,' " he said.
When he heard the news about the Norwood family, Hernandez said, he didn't think it was real.
"When I heard [a news report] say 'purple hair,' though," he said, "I just thought, 'Oh crap, that's him.' "