By CLAUDIA LAUER, Associated Press

CONWAY, Ark. (AP) — An Arkansas teenager pleaded guilty Tuesday to charges that he robbed and killed the couple who raised him as their grandson, sidestepping a possible life term in prison.

Justin Staton, who is now 15 years old, pleaded guilty to two counts of first-degree murder and other charges related to the 2015 shooting deaths of Robert and Patricia Cogdell, who were both 66 years old. Faulkner County Circuit Court Judge Troy Braswell accepted the change of plea and the agreement for Staton to testify against the other teens charged in the shootings, including Hunter Drexler.

Staton teared up as Braswell sentenced him to 35 years in prison. He had faced up to life in prison for the charges.

The Cogdells weren't Staton's biological grandparents, but they raised the boy even after discovering via genetic testing in 2008 that their son, Robert Shane Cogdell, was not Staton's father.

"I hope every day for the rest of your life, you think about them," Braswell told Staton. "Because they loved you and took care of you. ... and the thanks you gave them was murder."

Drexler, who was 17 at the time of the shootings, has pleaded not guilty to two charges each of capital murder, aggravated robbery, theft of property obtained by threat of serious physical injury and abuse of a corpse.

Prosecutors said Staton agreed to give them access to his iPod and to text messages between him and Drexler that would show Drexler's role in planning and acting out the killings. Prosecutors had asked for help from the FBI to gain access to the iPod and an iPhone belonging to Drexler.

Deputy Prosecutor Hugh Finkelstein said prosecutors have looked at the information on Staton's iPod, but would not comment on the content. He said the office has not been able to access Drexler's iPhone yet.

Prosecutors allege the pair robbed and shot the Cogdells at their Conway home, about 30 miles north of Little Rock, then dumped their bodies in a wooded area nearby. Two other teens, Connor Atchley and Anastasia Roberts, both 17, were charged as adults with first-degree murder and theft by receiving.

Prosecutors allege all four were present for the killings and that the three boys came up with the plan to kill the Cogdells while they were in a juvenile detention center together.

Finkelstein read a summary of the events that Staton had agreed to plead guilty to. He said the guns were brought to the house by Drexler, both Drexler and Staton were armed during the encounter and that both the teens helped move the bodies to the tree line behind the house with Staton using a front loader.

Finkelstein said Drexler had cut Robert Cogdell's pockets and taken about $3,000 in cash as well as credit cards, some of which he used to purchase a burner phone with prepaid minutes. He said when Staton was arrested at his mother's house he had Robert Cogdell's blood on his shirt and shoes.

While on the stand, Staton struggled to hold back tears as he gave simple "yes sir" and "no sir" answers to the judge's questions. He declined to give a statement after entering his plea.

The 35-year sentence for first-degree murder will run concurrently with a 35-year sentence for aggravated robbery, a 20-year sentence for theft, and a 10-year sentence for abuse of a corpse.

Staton's relatives filled a handful of rows in the courtroom. Several of them murmured when the sentence was announced and sniffled as they left the courtroom. Several relatives, including his maternal grandfather, declined to comment on the hearing.