LOS ANGELES, June 30 (Xinhua) -- A federal agency was investigating whether some Marines shot a group of prisoners to death in Fallujah, Iraq in 2004, it was reported Saturday.

    The Naval Criminal Investigative Service (NCIS) was conducting the probe into whether five to 10 Marines from California violated the laws of war, according to the North County Times, a local newspaper in California.

    The newspaper said NCIS has interviewed about 20 people so far and some have been read their rights, said the paper, quoting military and legal sources with direct knowledge of the investigation.

    Under the Uniform Code of Military Justice, the killing of a captured enemy combatant who does not present a threat is considered murder, the newspaper reported.

    Some of those being questioned are no longer in the Marine Corps, and at least one has hired a private defense attorney who specializes in military law, according to the newspaper.

    The Marines are believed to have been involved in the deaths of as many as eight people who were captured during one of the largest battles of the Iraq war, said the paper.

    It was unclear whether the Iraqis had been declared prisoners, whether any or all were bound in any way, and where specifically the slayings took place, the newspaper reported.

    The shootings reportedly happened on or about Nov. 10, 2004, three days after the United States launched a major assault in Fallujah, a city in western Iraq that at the time was under insurgent control, the newspaper reported.

    A source told the paper the troops believed they were carrying out the orders of their commanders when the alleged insurgents were shot.

    An NCIS official would not comment on the report, according to the newspaper.