Pat Dollard | Young Americans

SAN DIEGO (AP) - The highest-ranking U.S. serviceman to face court-martial involving combat since Vietnam was ordered to trial Friday for failing to investigate the killings of 24 Iraqis, including women and children, in Haditha two years ago.

Another Marine was also ordered to face court-martial for charges including involuntary manslaughter.

Lt. Col. Jeffrey R. Chessani faces charges of dereliction of duty and violation of a lawful order on allegations that he mishandled the aftermath of the Nov. 19, 2005, shootings, which followed a roadside bombing that killed a Marine driver.

Chessani was commander of the Camp Pendleton-based 3rd Battalion, 1st Marine Regiment that has been the focus of the biggest prosecution of U.S. troops in the Iraq war.

He is the most senior U.S. serviceman since the Vietnam War to face a court-martial for actions or decisions made in combat, said Gary Solis, a former Marine Corps prosecutor and judge who teaches law of war at Georgetown University Law Center.

One of Chessani’s men, Lance Cpl. Stephen B. Tatum, was ordered to face a court-martial on charges of involuntary manslaughter, reckless endangerment and aggravated assault. He is one of four Marines originally charged with murder in the killings.

The decision by Lt. Gen. James Mattis to send Tatum to court-martial comes after the investigating officer said last month that the evidence was too weak to prosecute him. But Tatum will not be tried on the murder count he originally faced.

Tatum, of Edmond, Okla., shot and killed civilians, but “he did so because of his training and the circumstances he was placed in, not to exact revenge and commit murder,” Lt. Col. Paul Ware wrote last month in recommending he not face court-martial.

Chessani’s civilian defense attorney, Brian Rooney, told The Associated Press he was disappointed with the general’s recommendation.

“I can tell you this decision by Gen. Mattis today is going to have a negative affect on all officers, including battalion commanders,” he said, adding it would undermine the trust between commanders and their troops. “Are they going to be able to trust the word of their junior officers, senior enlisted and junior enlisted?”

If convicted on all counts, Chessani faces up to three years in prison.

He is the second colonel to be court-martialed over actions in Iraq. Army Lt. Col. Steven L. Jordan of Fredericksburg, Va., was convicted of abusing detainees at Abu Ghraib prison, said Tom Umberg, a retired Army colonel and former military prosecutor

The decision to send Chessani to trial mirrored the conclusion the hearing officer reached at his preliminary hearing. Col. Christopher Conlin said Chessani “failed to thoroughly and accurately report and investigate a combat engagement that clearly needed scrutiny.”

In his report, Conlin, an infantry officer, blasted Chessani for failing to go to the scene of the November 2005 killings immediately after they had occurred, even though he knew 24 “neutrals” were dead.

“To not have made every attempt to be on scene as this action developed, or to not have at least reviewed this action in detail … is in itself negligent,” Conlin wrote. “The fact that one fireteam was solely responsible for 24 deaths in all direct fire actions should have solicited more than passing interest from the senior leadership of the battalion.”

At Chessani’s preliminary hearing, held in June at Camp Pendleton, several witnesses testified local Iraqis had complained to Chessani in the days after the killings and that he promised to look into what had happened.

But Chessani said he never ordered a formal investigation because he believed the deaths resulted from lawful combat.

Lt. Col. Sean Gibson, a spokesman for the Marine Corps at the U.S. Central Command, which includes Iraq and Afghanistan, said Chessani and Tatum will be arraigned on the charges and required to enter pleas. A date for those hearings has not been set.