Oklahoma City -- From the case of teen killer Sean Sellers in the 1980s to the tragic shootings that took 13 lives at Columbine High School in 1999, murders and attempted murders committed by children are phenomena that frustrate society and mental health professionals alike.
However, an Oklahoma City resident is working hard to determine what causes children to kill.
Dr. Herman Jones is a neuropsychologist who is often appointed by courts to determine if kids who kill or attempt to kill can be rehabilitated. According to Jones, many children who commit capital offenses don't have a realistic sense of the consequences their victims will suffer because of their actions.
"They don't go in with the anticipation that someone will be dead at the end of it," he said.
In 1999, Jones evaluated 13-year old Seth Trickey -- a Fort Gibson teenager who opened fired at his middle school, wounding five classmates.
Trickey was a high achiever and was devastated when he didn't get an "A" in one of his classes. Jones said the intense pressure of trying to achieve good grades that overwhelmed Trickey is not uncommon among adolescents.
"I think that the expectations we have on children and youth are much greater," he said.
In addition to pressure, Jones said, the almost daily images of violence that bombard kids in video games and movies may have an effect on their mental health. He said other children lose the capacity to empathize -- either because of abuse at home or, in some cases, because feelings of empathy are not part of their mental functioning.
"The terms we've used in the past to describe these kids have been terms like sociopath or psychopath," Jones said.
Jones pointed to Sellers as an example of someone who lost the ability to empathize because he had no emotional connection with an adult.
In 1985, Sellers -- who was 16 at the time -- killed his parents while they slept. He was convicted of the crime in 1986 and was executed at the Oklahoma State Penitentiary in 1999.
At the time, some described Sellers' behavior in simplistic terms, blaming Satanism, heavy metal music and role-playing games. However, Jones warned that cases like Sellers' are reminders that adults should watch for kids who become withdrawn.
"Many kids who I see are throwaway kids who don't have an emotional connection with an adult in their life," he said.
A lack of emotional attachment may have also played a role in one Oklahoma girl's tragedy.
"Tracy," whose identity was withheld for this story, said she was constantly moved around as a child and was abused by her mother's boyfriend. When she was a teenager, Tracy was convicted and sentenced for killing an infant.
She said the anger and isolation she felt leading up to the crime went unnoticed by those around her.
"Nobody cared what was happening to me, and nobody could do nothing about it & and nobody was going to do anything about it," she said.
Tracy said she held everything inside, feeling she couldn't turn to anyone for help.
However, she said help finally came after she was sentenced. Confined to a juvenile detention facility, Tracy went through intense counseling.
"They weren't going to move," she said of her counselors. "They'd sit in there all day until you got up enough nerve to admit what you've done."
Tracy said she let everything out during her counseling session because she felt comfortable with the notion that someone would finally listen to her problems. Now out of custody, Tracy has a job and hopes to go back to school to become a veterinarian.
"As long as I make it that way, I have control over my life and what I want to do," she said.
But Tracy said she would never forget that her brighter outlook comes at a cost -- the life of a young girl.
"I can't change it," she said. "I can't bring her back."