SAN DIEGO (AP) — The military's highest court overturned a murder conviction against a Camp Pendleton Marine in one of the most significant cases against American troops from the Iraq war.

The Court of Appeals for the Armed Forces threw out the conviction of Sgt. Lawrence Hutchins III of Plymouth, Mass., who has served about half of his 11-year sentence.

According to the ruling posted on the court's website Wednesday, the judges agreed with Hutchins, who claimed his constitutional rights were violated when he was held in solitary confinement without access to a lawyer for seven days during his 2006 interrogation in Iraq.

The decision is seen as a major blow to the military's prosecution of Iraqi war crimes.

Hutchins led an eight-man squad accused of kidnapping an Iraqi man from his home in April 2006, marching him to a ditch and shooting him to death in the village of Hamdania.

Hutchins has said he thought the man — who turned out to be a retired policeman — was an insurgent leader. Prosecutors accused the squad of planting a shovel and AK-47 to make it appear he was an insurgent.

None of the other seven squad members served more than 18 months.

The move is the latest in a series of twists and turns for Hutchins, whose case already was overturned once by a lower court three years ago.

The lower court ruled Hutchins' 2007 trial was unfair because his lead defense lawyer quit shortly before it began. The military's highest court disagreed on that point and reinstated Hutchins' conviction in 2011, sending him back to the brig after eight months working at a desk job at California's Camp Pendleton. The high court said at the time that the problem wasn't grave enough to warrant throwing out the conviction.

On Wednesday, it agreed with Hutchins' latest petition.

Hutchins' lawyer, Babu Kaza, said he expects him to now be released in days.

"Sgt. Hutchins and his family have suffered enough with this case, and it's time for this to be over," Kaza said. "Enough is enough."

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The Navy can appeal to the Supreme Court or send the case to the convening authority, who can either order a retrial or let the ruling stand.

Navy officials could not be immediately reached for comment.

In their ruling Wednesday, the court's judges said the Naval Criminal Investigative Services violated Hutchins' Fifth Amendment rights when it interrogated him in May 2006 about the incident and then put him in a trailer in Fallujah with no access to a lawyer or phones.

After seven days, the same Navy investigator returned and asked Hutchins for permission to search his belongings. Hutchins said he asked to tell his side of the story and was told he could do so the next day, when he waived his right to counsel and provided a sworn statement about the crimes.

The judges ruled much of the case rested on that confession, which they determined was illegally obtained after Hutchins was held under guard for seven days.

"Accordingly, under the circumstances of this case, it was error for the military judge to admit the statement made by Hutchins on May 19, 2006," the judges concluded in their ruling.

The case was among the most serious Iraqi war crimes prosecuted by the government. In another major case that took six years, the lone Marine convicted in the killings of 24 unarmed Iraqi civilians in a raid in Haditha seven years ago reached a deal to escape jail time.

Another case involved the November 2004 death of an unarmed Iraqi detainee in Fallujah. One Marine was spared prison time after pleading guilty to dereliction of duty, and another was acquitted. Their former squad leader was acquitted in federal court.

Former Navy officer David Glazier, a professor at Loyola Law School in Los Angeles, said Wednesday's ruling demonstrates the military's poor prosecution record.

"For these very serious allegations of conduct that one would think of as war crimes, the military justice system has not performed very well in the past couple decades," Glazier said.

"Here this guy's conviction is overturned on the basis that he was mistreated by the government during his initial apprehension, and yet he's already served five years in prison," he added. "If the conviction was unjust in the first place, it's kind of appalling it's taken the military justice system five years to resolve it."

Hutchins' lawyer said his client told him after the ruling that he can't wait to return to his wife and two children.