Vincet Romero, 29, and Timothy Romans, 39, of San Carlos, Ariz., were found fatally shot on Wednesday in an eastern Arizona home. One victim was just outside the front door, while the other was found dead in an upstairs room. Both men were killed with a 22-calibre rifle in a small town of St Johns, Arizona.

An 8-year old Arizona boy, was accused of killing two adults. The boy first said he knew nothing about the murder, but later confessed everything. Police said the boy confessed he planned the killings. The minor was charged with two counts of premeditated murder. He shot each victim at least four times, stopping and reloading as he killed them.

“This is precedent-setting. We're going to charge an eight-year-old with two counts of homicide,” local police chief Roy Melnick was quoted as saying.

Police arrived at the scene within minutes after the neighbours reported hearing gunfire. They said the boy appeared at their door and said he “believed his father was dead.”

Judge Michael Roca of the Apache County Superior Court ordered a psychological evaluation of the boy. Prosecutors said there was no record of any complaints filed about the boy with Arizona Child Protective Services. Also, he had no disciplinary record at school.

It’s rare for kids and adolescents to commit homicide. According to FBI statistics, 62 children aged 7 or 8 were arrested on murder charges between 1976 and 2005. In two cases, parents were the victims of their own kids. There were no murder defendants under the age of 9 in the past 3 years, according to the FBI’s Uniform Crime Report lists.

What is behind all these cases? Psychologists say in these cases, the child or the teenager usually acts for one or more reasons, from years of physical or sexual abuse to severe mental illness. In rare cases, the child may have extreme antisocial and psychopathic tendencies.

The majority of homicides committed by children under 11 involve physical, emotional or sexual abuse in the home. Experts say that many of these kids who decide to commit such horrible homicides suffer from some level of traumatic stress disorder.

Another possible reason is a broken home, experts say. The 8-year old boy who allegedly killed his father and another man, systematically reloading a rifle and firing at close range, lived with his father in the two-story home in St. Johns. The child’s birth mother lives in Mississippi. The two broke up and the boy’s father remarried in September. His wife was not in town when the crime took place. Neighbours said that they were all “good people.” Investigators said they had found no evidence of trauma.

Furthermore, another element in the case may contribute to a plausible explanation: the boy was familiar with shooting. He and his father reportedly hunted prairie dogs together. He knew how to use a weapon. Was this reason enough to commit homicide?