Justin Staton, the 14-year-old suspect in the killings of his grandparents in Conway, now faces eight charges, among them two counts of capital murder.
One of the three "persons of interest," 17-year-old Hunter John Drexler, of Clinton, also faces two charges of capital murder, Prosecuting Attorney Cody Hiland said at a news conference Friday.
In addition to the capital murder charges, Staton and Drexler each face two felony charges of aggravated robbery, theft of property, and abuse of a corpse.
Staton was arrested after the bodies of Robert and Patricia Cogdell, both 66, were found on July 21 outside their home on Conway's west side.
The two other 17-year-old "persons of interest," Conner Hunter Atchley and Anastasia Rose Roberts, were transported with Drexler to Conway from north-central Texas after being classified as runaways.
Investigators declined to comment on the status of Atchley and Roberts on Friday.
Hiland said Staton and Drexler are charged as adults, adding that "the facts in this case allow us to do that."
During the news conference at the Conway Police Department, Police Chief AJ Gary said detectives have been working "around the clock" on the case.
Hiland said he anticipates that additional charges will be filed in the case.
An affidavit released Friday provided more information into the background of the case, including that Staton had threatened bodily harm to his grandparents and himself.
The document further describes Staton's relationship with Drexler and allegations of how the killings and a robbery plan unfolded.
"Justin advised that Hunter suggested that the grandparents be shot and killed. Justin advised that he thought Hunter was kidding but when his grandparents arrived, Hunter shot both of them," the affidavit states.
According to the affidavit, Staton shot his grandfather, who did not die immediately, one or two more times after one of the "persons of interest," Roberts, told Staton to put Robert Cogdell "out of his misery."
Atchley told investigators that the plan, conceived while he, Staton and Drexler were in juvenile jail together, was to kill Staton's grandparents, split a large some of money and run away.
Read more in Saturday's Arkansas Democrat-Gazette.