Staff Sgt. Johnny M. Horne Jr., 30, of Winston-Salem, N.C., was charged with the Aug. 18 slaying in Baghdad's Sadr City, the scene of fierce clashes earlier this year between coalition forces and Shiite rebels allied to firebrand anti-U.S. cleric Muqtada al-Sadr.
Horne was expected to be sentenced Friday, the military said.
Meanwhile, details began to emerge Friday about the composition of a 228-candidate list presented by Iraq's mainstream Shiite groups in the run-up to next month's parliamentary elections, part of their bid to take a leading role in post-occupation Iraq.
In other developments:
Horne, a member of Company C, 1st Battalion, 41st Infantry Regiment, Fort Riley, Kan., also pleaded guilty to a charge of soliciting another soldier to commit murder.
He is one of six Fort Riley soldiers charged with killings in recent months — two for slayings in Kansas and four for deaths in Iraq.
"The convictions stemmed from Staff Sgt. Horne's murder of a severely wounded Iraqi civilian in Baghdad's Sadr City district," a military statement said.
Previous military court hearings have heard that several troops fired on a group of Iraqi men placing homemade bombs along a road in Sadr City, an impoverished Baghdad neighborhood.
Soldiers from the same battalion arrived on the scene to find a burning truck and casualties around it.
According to accounts given by witnesses at previous hearings, the soldiers, including Horne, tried to rescue an Iraqi casualty from inside the truck. The victim had severe abdominal wounds and burns and was thought by several of the witnesses to be beyond medical help.
The criminal investigator had said that the U.S. soldiers had decided that "the best course of action was to put (the victim) out of his misery."
Another military hearing into a soldier charged with killing another Iraqi in a separate August incident in Sadr City is expected to continue Friday.
Sgt. Michael P. Williams, 25, of Memphis, Tenn., faced the opening day of an Article 32 hearing Thursday charged with premeditated murder, obstruction of justice and making a false official statement.
Two witnesses gave evidence during the Article 32 hearing, which is the military equivalent of a grand jury hearing.
Williams is charged in the same case along with Spc. Brent May, 22, of Salem, Ohio, who faced a two-day hearing this week and is awaiting a ruling on whether he will be court-martialed, receive a lesser penalty or be acquitted.
Six members of his unit, Company C, 1st Battalion, 41st Infantry Regiment, from Fort Riley, testified in his case.
Earlier this week in Germany, a U.S. tank company commander accused of killing a critically injured Iraqi driver for al-Sadr was ordered court-martialed.
Capt. Rogelio Maynulet, 29, of Chicago, will be tried on charges of assault with intent to commit murder and dereliction of duty, which carry a maximum combined sentence of 20½ years, said military spokesman Maj. Michael Indovina.
During Maynulet's Article 32 hearing, witnesses testified that the driver had been shot in the head when Maynulet saw him. A fellow officer said Maynulet told him he then shot the man out of compassion.
As expected, representatives of Iraq's dominant Iran-linked Shiite party topped the list of the United Iraqi Alliance.
Abdel-Aziz al-Hakim, the Supreme Council for the Islamic Revolution, was number one, said one of his aides. But there were also representatives of small northern Sunni tribes, Turkomen movements and others in an apparent attempt to attract wide support.
Members of participating groups said the coalition's platform, which has not been finished, would include a call for working toward the withdrawal of U.S. and other foreign troops in Iraq.
The candidates list had been in the works for weeks and now puts the focus squarely on Iraq's Sunni Arab groups, who must decide whether to continue seeking a postponement of the vote, boycott it, or join the race.
One Sunni Arab group that had called for a delay, the Iraqi Islamic Party, quietly submitted a 275-candidate list Thursday. Party officials told The Associated Press they wanted to reserve the right to take part in the vote if the election is not postponed.
The election will be Iraq's first popular vote in decades. Iraqis will choose a 275-member assembly that will write a permanent constitution. If adopted in a referendum next year, the constitution would form the legal basis for another general election to be held by Dec. 15, 2005.
The 228 candidates also include independent Sunni Muslims, members of the Yazidis minority religious sect and a Turkomen movement, among others.