A military court has agreed to review an appeal for a new trial by an Oklahoma soldier convicted of murdering an unarmed Iraqi prison detainee after interrogating him at gunpoint.

The U.S. Court of Appeals for the Armed Forces, in a ruling published Friday, said it will examine 1st Lt. Michael Behenna's claims that his military trial wasn't fair because the judge gave the jury faulty instructions and prosecutors failed to disclose favorable information to the defense.

Behenna, 28, is serving a 15-year sentence at Fort Leavenworth, in Kansas for his 2009 conviction for unpremeditated murder in a combat zone. He was initially sentenced to 25 years, but the term was reduced twice.

His mother, Vicki Behenna, said her son would have no way of knowing about Friday's ruling and that she and his father planned to drive to the fort from their home in Edmond on Saturday to give him the news.

"Oh God, I feel like we've got a little bit of hope," she told The Associated Press by phone.

"The only thing we've ever asked for is that Michael receive a fair trial and that the jury get all the evidence," said Vicki Behenna, who is an assistant U.S. attorney for the western district of Oklahoma.

Prosecutors alleged during his trial that Behenna took detainee Ali Monsour Mohammed to a secluded railroad culvert and shot him execution-style after interrogating the man at gunpoint about an April 2008 roadside bombing that killed two men under Behenna's command.

Behenna said he defied orders to release the man because he wanted another chance to question him, and that he killed the detainee in self-defense after the man stood up and reached for his gun.

Behenna's attorneys contend that a prominent forensics expert hired by the government concluded that Behenna's version of events was not only possible, it was the only logical explanation consistent with the forensic evidence.

The expert never testified at the trial, and Behenna's attorney learned of his conclusions only after the court returned a guilty verdict.

The military trial judge denied a defense motion for a mistrial, ruling that there was no reason to believe the expert's testimony would have led to a more favorable result for Behenna. And the U.S. Army Court of Criminal Appeals upheld rejected Behenna's conviction and sentence in July.

A hearing date for the review had not set. But Behenna's father, Scott Behenna, told The Oklahoman, which first reported about the ruling, that the hearing may occur this spring.

The Army did not file a response to the latest appeal and relied on arguments it made to the Army appeals court: that Behenna had no legitimate self-defense claim because he was dressed in full battle gear and had a loaded pistol pointed at the naked, unarmed detainee and that there were no trial errors serious enough to warrant to reversal in the case.

Vicki Behenna said her son has remained positive in prison and passes the time reading and learning Spanish.

"I was so worried that Michael would become angry and bitter," she said. "And he's not done that, he's stayed hopeful."