CONWAY, Ark. -- A 14-year-old boy shot and killed his grandparents during a robbery-and-murder scheme hatched while he and two other friends were held in an Arkansas juvenile jail, police and prosecutors said Friday.Justin Staton, along with Hunter Drexler, 17, were each charged as adults with two counts of capital murder Friday in the July 22 deaths of Robert and Patricia Cogdell at their home in Conway, about 30 miles north of Little Rock. Police said the teenagers shot the couple and dumped their bodies in a wooded area nearby.According to an affidavit filed with the charges, Staton told officers that, after complaining to Drexler about his grandparents, Drexler suggested that he shoot them. Another 17-year-old boy who was at the home at the time of the attack told officers the plan had been conceived while all three were in juvenile jail together."Justin's plan was to shoot and kill his grandparents, split a large sum of money and credit cards between the three of them and then they would all run away," the affidavit said. "Justin estimated their take at $50,000 to $90,000."A 17-year-old girl also at the home when the Cogdells were shot told police that Robert Cogdell didn't die immediately and was "choking and gurgling" on the floor outside his bedroom."She told Justin that he needed to do something about the noise Robert was making and suggested that Robert be put out of his misery," the affidavit said. "Justin walked over and shot Robert 1 or 2 times."Drexler and the other teenagers were detained in Texas days after the killings and found with some of Robert Cogdell's personal and work credit cards. The other teenagers were not charged with any crimes.Without speaking specifically about Staton or Drexler, Prosecutor Cody Hiland blamed a culture that would let young people behave outside societal norms."If the law would allow for you to come into our juvenile courts, you would see young men and young women who are lonely, and they are angry and they are bitter, because their mom and dad have checked out to pursue whatever immediate gratification is driving them at the time," Hiland said."It's the breakdown of the family. Faith issues. Societal issues," he said. "I can tell you that our juvenile courts are full and that one day we will reap a bitter harvest when they grow up."Police had said previously that Staton quickly emerged as a suspect. In May, the Cogdells had called police because the teenager was threatening suicide and had become verbally abusive. In January, Robert Cogdell and Staton had fought after finding marijuana in the boy's room and $300 missing from the grandfather's wallet.Staton had lived with his grandparents but was arrested at his mother's house with $1,540 in a pants pocket. During one of two interviews with police on July 22, Staton cried a little and said, "I'm so sorry. I don't know why I did it."Staton, of Conway, and Drexler, of Clinton, were also charged with two counts each of aggravated robbery, theft of property and abuse of a corpse.