CAMP PENDLETON -- Lance Cpl. Stephen Tatum saw the child -- young, dark-haired, wearing a white T-shirt and standing on a bed in his Haditha home -- but pulled the trigger, an investigator testified Wednesday that Tatum told him.

"There was a pause, a little hesitation, and then he said, 'That's the room where I saw the kid that I shot. Knowing it was a kid, I shot him anyway," Naval Criminal Investigative Service agent Matthew Marshall said Tatum told him during an interrogation four months after the shooting.

Tatum's attorneys dispute Marshall's contention and say Tatum never swore to or signed the statements that Marshall said Tatum made. They also argue that the statements attributed to their client, a 26-year-old Oklahoma native, are inadmissible in court.

The lance corporal is one of three Marines charged with the deaths of some of the 24 Iraqis killed in Haditha on Nov. 19, 2005. The case is the largest war crimes prosecution to emerge from Iraq since the U.S. invasion in 2003.

Tatum is in a Camp Pendleton courtroom this week for an investigative hearing, much like a preliminary hearing in civilian court, to determine if there is enough evidence to send him to trial.

NCIS agents also testified about their interviews with a 6-year-old boy and his 10-year-old sister who survived but were orphaned in the attack on their home.

Prosecutors say Tatum and other Marines stormed homes and killed 24 Iraqis in retaliation for a bombing that shredded a Humvee in their convoy. The bombing killed Lance Cpl. Miguel "TJ" Terrazas and wounded two others.

Attorneys for Tatum and his co-defendants say the Marines were the target of enemy gunfire after the explosion, and had run into the homes to chase their attackers.

Tatum is accused of killing people in the first two of the four houses the Marines stormed that day in search of insurgent fighters. His attorneys said this week that their client was following orders and defending himself properly in combat.

Marshall, testifying as a prosecution witness, said Tatum told him that he and three other Marines followed a fleeing person from the first home to the second. There, they shot a man at a door and lobbed a grenade into a washroom, Tatum said

While searching the home, Tatum heard his squad leader, then Sgt. Frank Wuterich, firing his gun, so he ran into the room and also fired at the people inside, according to Marshall's testimony about what Tatum told him.

"At that time, he stated that he'd (identified) them as women and children," Marshall said. "I asked if he shot them, and he said yes. He was very emotional about it, very sorry to the point that he cried."

In a later interview, Marshall testified, Tatum again told him he knew the people were women and children.

"He stated that women and children can hurt you, too, as justification for shooting them," Marshall said.

Tatum's attorney, Kyle Sampson, often sparred with Marshall through a lively cross-examination, during which Marshall said he did not record any of his interviews with Tatum, in accordance with NCIS policy. Marshall said the reports he generated after questioning Tatum were "factual representations" of what he said Tatum told him.

Marshall also acknowledged that Tatum had told him at least once that he had "unknowingly" shot women and children.

Tatum was first questioned by NCIS agents in what the case's lead agent, Brian Brittingham, testified was the only room the Marines made available to them -- the same urine-smelling, concrete subterranean room in Haditha where Marines had interrogated Iraqis.

That first session with NCIS lasted more than 12 hours.

While on the stand, Brittingham also said he interviewed Eman Waleen Al Hameed, a 10-year-old girl who survived when the Marines stormed her home. Her parents were killed in her home, also a set of her grandparents, an aunt and a 4-year-old brother.

"She said the Americans raided her house and killed her family and left," Brittingham said of an interview he did with her four months after the deaths.