The military's highest court agreed Monday to hear the appeal of a U.S. Marine convicted of murder in one of the most significant criminal cases against U.S. troops from the Iraq war.

The Court of Appeals for the Armed Forces ordered a review requested by Sgt. Lawrence Hutchins III, who claimed in a petition that his constitutional rights were violated when he was held in solitary confinement without access to a lawyer for seven days during his interrogation, and that Navy Secretary Ray Mabus unlawfully influenced his case after his conviction.

Hutchins, 26, of Plymouth, Mass., led an eight-man squad accused of kidnapping retired Iraqi policeman Hashim Ibrahim Awad from his home in April 2006, marching him to a ditch and shooting him to death. The killing took place in Hamdania, a small village in Al Anbar province.

The six other Marines and a Navy corpsman in his squad served less than 18 months.

Hutchins has sought clemency and early release, saying he was deeply sorry for what happened and has suffered nightmares and anxiety because of the killing.

Those requests have been denied, Hutchins claimed in the appeal, because Mabus illegally interfered in the case and influenced officers under him to rule against release.