SAN DIEGO - A military judge at Camp Pendleton on Tuesday dismissed charges against Lt. Col. Jeffrey Chessani, the highest-ranking officer accused in the deaths of 24 Iraqis in 2005 in the town of Haditha.

Col. Steven Folsom, the judge, made his ruling in response to a motion from defense attorneys charging that undue influence was exercised on the convening authority in the case. Folsom dismissed the charges without prejudice, meaning the Marine Corps could refile them.

Defense attorneys had asserted that Gen. James N. Mattis, while he was the convening authority, was unfairly influenced by politicians, the media and a Marine lawyer in bringing charges against Chessani and seven other Marines. Mattis, grilled by defense lawyers, denied being influenced.

"The appearance of unlawful command influence is as devastating as actual manipulation of a trial," Folsom said.

A major point of contention was the defense assertion that Mattis erred by allowing Col. John Ewers to be present while the general discussed the Haditha case with prosecutors at several meetings. Ewers had been involved earlier with the preliminary investigation that led to a more thorough investigation by Naval Criminal Investigative Service agents.

Ewers testified that he did not speak to Mattis about Haditha and only attended the meetings because he had other cases to discuss with him. But defense attorneys said his presence at the meeting constituted undue influence.

The incident in Haditha occurred Nov. 19, 2005, after a roadside bomb exploded beneath a Humvee, killing a Marine and injuring two. Other Marines from Chessani's battalion killed five men outside their car and then 19 other Iraqis, including three women and seven children, while searching three nearby houses for insurgents.

Chessani was charged with dereliction of duty and failure to obey an order in not investigating the killings more thoroughly. He was the highest-ranking Marine officer to face charges from the wars in Iraq and Afghanistan.

Chessani plans to retire but would be kept on active duty if charges were refiled.

Initially four enlisted Marines were charged with the killings and four officers with dereliction of duty or related counts. But the prosecution case, from the beginning, was hampered by contradictory testimony, skimpy forensics and the refusal of Iraqi witnesses to come to Camp Pendleton for the court proceedings out of fear for their safety.

Chessani is the third officer to have charges dropped. The only defendant whose case went to court-martial, Lt. Andrew A. Grayson, was found not guilty by a jury of seven officers. Charges were dropped against three of the four enlisted defendants in the case. Staff Sgt. Frank D. Wuterich, the squad leader who led the charge into the houses, still faces trial.

Chessani was on his third combat tour in Iraq. Devoted to his Marines, the normally mild-mannered Chessani was quoted by one witness during his preliminary hearing as shouting at one of his officers that he refused to think his men had committed murder.

The criminal cases might never have been filed except for an expose in Time magazine four months after the killings. Until then, the deaths had been considered a tragic byproduct of an attack on a Marine convoy by insurgents. Only when top brass learned the magazine was investigating did the military launch its own investigation.

Three senior officers -- a two-star general and two colonels -- received letters of censure for not investigating the incident further.

tony.perry@latimes.com

© 2008 The Los Angeles Times