Kieshawn Mann's supporters say he is shy and someone every parent would want their child to play with.
But the Kentwood, Mich., 13-year-old has been charged with the premeditated murder of his mother's fiance -- allegedly shooting Jermelle Stokes at point-blank range as the man was using the computer.
The boy claims the Jan. 24 shooting was an accident, telling police, "the gun went off and the finger was in the trigger."
But his 12-year-old friend has told the court that Mann had brought the gun to school and told him he was planning to kill Stokes because his soon-to-be stepfather had abused his mother.
The number of young children who kill is small, but edging up after reaching an all-time high a decade ago.
The murder arrest rate in 2008 was 3.8 arrests per 100,000 juveniles ages 10 through 17. This was 17 percent more than the 2004 low of 3.3 and three-quarters less than the 1993 peak of 14.4, according the Office of Juvenile Justice and Delinquency Prevention.
In the most comprehensive survey to date, "Children's Exposure to Violence," the U.S. Justice Department suggests that most U.S. children are exposed to violence in their daily lives, with more than 60 percent reporting exposure within the past year.
"These kids have been either abused or seen abuse or they have been exposed to violence somewhere in their life," said psychologist Herbert Nieburg, associate professor of justice and political studies at Mitchell College in New London, Conn. "And some are just angry kids who want to get even."
Mann initially told police that someone had called his house threatening Stokes, according to ABC's affiliate WZZM.
"We kind of seen it cause I was coming up the stairs, we kind of seen it and then it was like 'pow' and I ran back downstairs to get them and make sure they was alright and I heard somebody come out the door and I don't know," Mann told the dispatcher in tapes obtained by WZZM.
But the classmate who testified against Mann last week said the 13-year-old had brought a gun to his elementary school. The friend offered to hide the gun in his locker "to be nice."
Just last week in Chariton, Iowa, 12-year-old Jacen Paul Pearson was charged with fatally shooting his stepfather and injuring a young girl.
When authorities arrived at the scene, they found the body of 37-year-old Todd Peek and a wounded 5-year-old, Cheyanne Peek.
Some remembered the victim as a caring father and baseball coach. But others described an abusive man who "berated and physcially abused" his step-son, according to the Des Moines Register.
In a highly publicized case last May, 11-year-old Jordan Brown of Wampum, Pa., was charged with shooting his father's pregnant girlfriend in the back of the head with a 20-gauge shotgun while she was resting in bed.
Authorities say after the killing, Brown got on the school bus and headed off for his fifth-grade class. The victim, 26-year-old Kenzie Marie Houk, was 8 months pregnant, and had "experienced problems" with the victim in the past, say local reports.
"An 11-year-old kid -- what would give him the motive to shoot someone?" Houk's father, Jack, told the Associated Press. "Maybe he was just jealous of my daughter and the baby and thought he would be overpowered."
Brown and his father reportedly used to practice shooting behind their western Pennsylvania farmhouse. The 11-year-old had received a shotgun as a gift for Christmas from his father and was a good shot, winning a turkey shoot just weeks before the shooting, beating out several adults.
The alleged murder followed another incident in Arizona, when a 9-year-old boy accused of shooting his father and his father's roommate pleaded guilty to negligent homicide.
"What springs up in these cases is poor impulse control, a degree of frustration and alienation and probably a high degree of disempowerment, feeling out of control and having to do something to control the situation," said Nieburg.
These baby-faced defendants are presumed innocent until proven guilty, but cases like these beg the question: Why do kids kill?
Psychosis, Hallucinations Can Trigger Murder
"If a kid is psychotic, hallucinating or delusional, they may think something has happened, like aliens invading or the person killed is doing something to them," he said.
"The key is you have to look at three things: the biological, the psychological and the socio-cultural," said Nieburg.
Biological factors can include brain damage, head trauma and lower intellectual and emotional functioning, as well as drugs, alcohol and even fetal alcohol syndrome.
Social factors like "how you grew up" and social messages can also be influences: "If you were born in the 'hood' as opposed to upper Fifth Avenue, even your religious beliefs," he said.
The family environment can also play a role in why some children are able to kill.
"If there is violence in the home there is a certain risk factor," said Murray Straus, co-director of the Family Research Lab at University of New Hampshire.
"The usual result is kids doing more hitting of other kids in the family and other unrelated kids, as well as attacks on their parents," he told ABCNews.com. "The single biggest predictor of when kids hit parents is how much the parents are hitting the child under the euphemism of spanking."
Some experts even suggest that watching violence on television and in video games promotes aggression in children, although that research is controversial.
Lt. Col. Dave Grossman, a West Point military psychologist who trains health professionals on how to prevent killing, contends violent programs desensitize children to violence.
With Gloria DeGaetano, a former police officer, he wrote the 1999 book, "Stop Teaching Our Kids to Kill."
"I predicted that we would soon see more 12-year-olds committing unspeakable crimes like mass murder," writes DeGaetano.
"Sensational visual images showing hurting as powerful and domination of others as permissible are dangerous."
But psychologists are confounded by why some children cross the line and kill. Why is one child exposed to violence propelled to kill and another is not?
"The critical issue is all these factors only affect the person at risk," said criminal psychologist Nieburg. "A lot of kids watch programs about suicide, but they don't do that. Certain kids are just predisposed to violence."
Meanwhile, Jordan Brown, now 12 and who has pleaded not guilty, is facing an adult trial, although his parents are trying to get the case moved to the juvenile justice system.
Pearson is also being charged as an adult, according to police.
And Kieshawn Mann, whose family and friends have crowded the Michigan courtroom for the pre-trial hearings this week to support him, is also facing adult charges in what police are calling a "cold-blooded killing."
According to relatives of the victim, Stokes had been a father figure to the 13-year-old since he was only 3.
"The entire family of the victim declined to talk," said ABC reporter Lambrini Lukidis, who is covering the trial for Michigan's WZZM. "They are close to the little boy -- even the mom of the stepfather. Obviously she is upset Stokes passed away, but she's not saying anything negative about the boy."
"Every time he is in court, 50 to 60 people show up in support of the little boy -- his mom, family members, other kids and their parents and people from the school," said Lukidis.
Legal analysts admit that it is heartbreaking to see small children faced with adult crimes and hard sentences.
"The decision to prosecute a child as an adult is a difficult one," said former New York district attorney and television court judge Jeanine Piro, who prosecuted a 12-year-old killer as an adult.
"The choice is not about being 'hard' or being compassionate," she writes on her blog about the Brown case.
"It is about recognizing the evil that accompanies a killer's choice to take the life of an innocent pregnant woman and mother of two, whose children will never get to hug their mother again because an angry 'boy' with a gun decided she should die."