The mother of a Marine who witnesses say covered a grenade with his body to save comrades in Iraq plans to appeal to Congress to award her son the nation's highest military honor after learning it was denied by Defense Secretary Robert Gates because of questions about his final act.

Rosa Peralta said Thursday she made the decision after a Marine general told her that her son, Sgt. Rafael Peralta, would be awarded the Navy Cross rather than the Medal of Honor because the nomination was tainted by reports he was accidentally shot by a fellow Marine shortly before an insurgent lobbed the grenade.

"I'm going to see what can be done, because I'm not satisfied with what they want to do now," she said in Spanish.

President Bush singled out the Marine's actions in a 2005 Memorial Day speech, saying Peralta "understood that America faces dangerous enemies, and he knew the sacrifices required to defeat them."

"The president spoke of him. So how is this now possible that they do this," Rosa Peralta said.

She said she was considering rejecting the Navy Cross, the second-highest award for valor in combat that can be awarded to a Marine. Peralta will be the 24th recipient of the Navy Cross for actions in Iraq and Afghanistan.

"I still don't know what I'm going to do," she said.

The question about whether to award Peralta the Medal of Honor centers on whether the mortally wounded Marine, who was shot in the head and upper body, could have intentionally reached for the grenade and covered it with his body.

"There was conflicting evidence in the case of Sgt. Peralta as to whether he could have pents, Peralta lay mortally wounded on the floor of a house and grabbed a grenade lobbed by fleeing insurgents. His body absorbed the blast and he died immediately.

In a rare move, the Marine Corps Thursday released a redacted copy of the Medal of Honor nomination by Lt. Gen. Richard Natonski and a investigative report detailing the "friendly fire" shooting of the sergeant.

The report found sufficient evidence existed to believe that Peralta was probably shot by a fellow Marine and that a gunshot wound to the head and injuries to the head from a grenade caused his death.

The nomination, which relies on witness statements, forensics, bomb fragment analysis and an autopsy, concluded that although Peralta was shot in the head, he made "a conscious, heroic decision to cover the grenade and minimize the effects he knew it would have on the rest of his Marine team."

The nomination details Peralta's actions in the final minutes of his life, with several witnesses recounting how the Marine lay face down and used his arm to pull the grenade to him. It also says a forensic analysis of Peralta's clothing and flak jacket show the grenade was underneath him when it exploded.

Peralta, who was assigned to Hawaii's 1st Battalion, 3rd Marine Regiment, moved to San Diego from Tijuana as a teenager. He was 25.