Massacre
 
Two dozen unarmed men, women and children were shot dead in the western Iraqi town on November 19, 2005.
 
The incident is one in a series of cases in which US service members have been accused, and in some cases convicted, of involvement in killing civilians.
 
Few details have been made public about the charges, although a US military investigation centred on a squad of marines lead by Staff Sergeant Frank Wuterich.
 
Earlier in the year, Wuterich sued John Murtha, a Democratic Representative, when he said US troops "killed innocent civilians in cold blood".
 
Captain Lucas McConnell, who was monitoring fighting in and around Haditha on the day of the incident, is also expected to face charges, his lawyer told Reuters.
 
McConnell may be accused of dereliction of duty for his reports on the incident.
 
Procedures
 
Once charged, the defendants are entitled to an Article 32 hearing, in which a military judge would decide if there is enough evidence to convene a court martial.
 
Iraqi witnesses say the marines shot civilians in their homes in retaliation over the death of Lance Corporal Miguel Terrazas, who was killed by a roadside bomb that exploded under a convoy rolling through Haditha, 96km north of Baghdad.
 
Defence lawyers dispute that version of events and say the men were engaged in a battle in Haditha after the bomb exploded and the civilians may have died during the fighting.
 
Two inquiries were launched into the incident, one into the shooting and another into the marines' procedures afterwards.
 
Earlier this year, George Bush, the US president, said that any US marine guilty of shooting Iraqi civilians would be punished. Nuri al-Maliki, the Iraqi prime minister, has called the Haditha killings a "terrible crime".