Updated

A Mississippi teen pleaded guilty Monday to reduced charges and agreed to testify against his co-defendants in the killing of a 6-year-old boy who authorities say was asleep in a car when it was stolen from a supermarket parking lot.

D'Allen Washington, 18, entered the plea to accessory after the fact to the kidnapping of Kingston Frazier, as well as to an unrelated robbery charge, before Madison County Circuit Judge William Chapman.

"Mr. Washington has accepted responsibility for his limited involvement in this matter, which led to the unfortunate and senseless murder of Kingston Frazier, and has agreed to offer state's evidence in the prosecution of the remaining co-defendants," lawyer Warren Martin said in a statement. "For his involvement, Mr. Washington continues to express his deepest condolences and sympathies to the family of Kingston Frazier."

Madison County District Attorney Michael Guest said Washington gave a statement under oath Monday outlining his actions and the actions of two co-defendants. Authorities say then-19-year-old Byron McBride stole the car and shot and killed Frazier.

"I think this is going to strengthen not only our case against Mr. McBride, but our ability to seek the death penalty," Madison County District Attorney Michael Guest told The Associated Press in a phone interview.

Frazier was sleeping inside a Toyota Camry in May 2017 when his mother left the car running in Jackson. Authorities say McBride got out of a car, leaving behind Washington and Dwan Wakefield, and stole the Camry. Miles away, police say McBride later shot Frazier, abandoning the car in muddy ditch with Frazier's body inside. Washington and Wakefield later picked up McBride, an act that led to the accessory charge.

Guest said he concluded that Washington was telling the truth when Washington said he didn't know Frazier was in the car or that McBride would kill Frazier.

"I am very confident that what he told us in this case was a truthful statement," Guest said, saying physical evidence also supports those conclusions. Guest said he believes Washington didn't learn of the shooting until he and Wakefield picked up McBride.

Guest said McBride could be tried as early as this summer, although he said there could be delays.

Wakefield, 17 at the time of Frazier's death, faces juvenile charges that could be upgraded to adult charges. Although Washington was also 17 at the time, his charges didn't go to youth court because he had already been charged as an adult in the unrelated robbery.

Washington remains jailed without bail because his bond on the robbery charge was revoked. McBride is also jailed without bail, while Wakefield is free on $275,000 bail.

___

Follow Jeff Amy on Twitter at: http://twitter.com/jeffamy . Read his work at https://www.apnews.com/search/Jeff_Amy .