The Oklahoma prosecutor who led the fight for justice for the heartbroken family of murdered Australian baseball player Chris Lane says he was not informed the youngest boy convicted in the random drive-by shooting was no longer in jail.
James Edwards, who was 15 in 2013 when Lane was shot in the back while jogging along a Duncan, Oklahoma, residential street and left to die, was sentenced to a maximum 25 years jail just two years ago.
Edwards received credit for time served and despite the expectation he would be behind bars until December next year, Oklahoma's Department of Corrections allowed Edwards out on its GPS monitoring device program on Thursday.
It's believed he has entered a sober living facility and is being monitored 24 hours a day, seven days a week.
"As I understand, he was a very well-behaved inmate," Oklahoma Department of Corrections public information officer Matt Elliott told AAP on Friday.
Stephens County District Attorney Jason Hicks, who prosecuted the case, believes Edwards should have remained in jail until he fully served his sentence.
"Normally, the department sends an email advising who will be released into the GPS program," Hicks said.
"I did not receive such notice in this circumstance and am looking into the situation at this time."
Lane's senseless and cold-blooded murder, along with the young age of the perpetrators, shook the rural city of Duncan and created headlines across the globe.
Edwards was a front-seat passenger in a Ford Focus on a hot August 13, 2013, afternoon.
The car was driven by 17-year-old friend Michael Jones and another friend, 16-year-old Chancey Luna, was sitting in the back seat.
They randomly spotted Lane, a 22-year-old from Melbourne who had a scholarship to study and play baseball at Oklahoma's East Central University, jogging along a residential street.
Lane had never met Edwards, Jones or Luna.
They drove up behind Lane, Luna reached forward, fired the fatal bullet from a .22 revolver out of the car window into Lane's back and Edwards sped off.
Lane fell to the ground and died gasping for breath before paramedics could save him.
Edwards, who became a prosecution witness, testified he was in the car rolling a marijuana cigarette and did not know Luna was going to fire the gun.
Edwards entered a guilty plea to an accessory to murder charge and had 10 years of his 25-year sentence suspended.
Luna and Edwards remain in custody.
Luna was sentenced to life in prison without the possibility of parole for first-degree murder but could receive a lesser sentence after America's highest court, the US Supreme Court, issued new opinions on juveniles sentenced to life without parole.
A new sentencing hearing will be held.
Jones entered a guilty plea to second-degree murder and was sentenced to life but could be eligible for release after 38 years.
Australian Associated Press
Sign up for our newsletter to stay up to date.