CAMP PENDLETON -- The Marine Corps announced Monday it has charged a sergeant with unpremeditated murder for the killing of an Iraqi detainee in Fallujah in 2004.

Sgt. Jermaine A. Nelson is the second person charged in the case in which four detainees were killed. The incident was first reported in the North County Times in late June.

A Marine Corps spokesman stressed that Nelson is considered innocent until findings show otherwise, adding that leadership at Camp Pendleton is committed to fully investigating alleged acts of wrongdoing in Iraq.

"Our message is to tell the citizens of the United States and the citizens of Iraq that we will fully investigate these matters and hold our own people accountable," Lt. Col. Chris Hughes said. "But we also stress that this Marine is innocent until proven guilty."

Although Nelson was charged last week, the Marine Corps did not announce the action until Monday for reasons that were not immediately clear.

Last week, the Los Angeles U.S. attorney's office filed a voluntary manslaughter charge against a former member of the same unit Nelson is from, alleging that Jose L. Nazario Jr. shot and killed two of the detainees.

After his appearance in U.S. District Court in Riverside, the 27-year-old Nazario maintained his innocence.

"I would just like to say that I am a U.S. Marine who fought for his country and I am innocent of these charges," he told reporters.

Nazario was a sergeant when he led a platoon of Camp Pendleton troops under investigation for the slaying of four Iraqi detainees on Nov. 9, 2004.

A criminal complaint included in charging documents filed against Nazario alleges he shot two detainees "in heat of passion caused by adequate provocation unlawfully and intentionally killed two unarmed male human beings."

The complaint includes an affidavit from Naval Criminal Investigative Service Special Agent Mark Fox, who wrote that Nazario and other Marines from Camp Pendleton's 3rd Platoon, Kilo Company from the base's 3rd Battalion, 1st Marine Regiment detained the insurgents during a house search.

The document contends that Nazario shot the two in the head at close range and that he directed other Marines to shoot two other Iraqis.

"Who else wants to kill these guys, because I don't want to do it all myself?" Nazario is quoted in the Fox affidavit as saying to his Marines.

The affidavit also states that Nazario told an unidentified Marine that the squad needed "to take care of them" so the unit could complete its assignment of moving to the center of the city, according to the affidavit.

A probe into the incident launched several months ago also is targeting one other former Marine as well as another man still in the service, according to a source with intimate knowledge of the investigation.

Nazario, who is free on a $50,000 property bond, is being prosecuted in federal court because he no longer is in the service and therefore the military does not have legal jurisdiction.

The fight for Fallujah was one of the major battles of the Iraq war.

On Nov. 6, 2004, a main group of troops from Camp Pendleton's 3rd Battalion, 1st and 5th Marine Regiments, along with supporting Marine units and U.S. Army forces, launched an assault to wrest control of the city from insurgents.

Intense fighting took place during the next week, with the final resistance cleared by late December. Several Camp Pendleton Marines were later honored with awards, including two Navy Cross citations for valorous actions during the fighting.

Ninety-five U.S. service members were killed and more than 600 were wounded. An estimated 1,350 insurgents were killed and 1,000 captured.

The rules of engagement were loosened during the battle because U.S. and Iraqi authorities had spent a week telling residents to leave and dropping leaflets over the city warning that a battle was coming.

Despite that, the law of armed conflict that governs the military forbids the shooting of any enemy combatant who has been disarmed and does not pose a threat.

See Tuesday's North County Times for more on the latest developments in the case.

Contact staff writer Mark Walker at (760) 740-3529 or mlwalker@nctimes.com.