A Marine assigned to take photos of the 24 Iraqi civilians killed in Haditha testified Thursday that he was later ordered to destroy the images.

Staff Sgt. Justin Laughner was called as a witness at a preliminary hearing for Lt. Col. Jeffrey Chessani, one of four officers charged with dereliction of duty for failing to investigate the Nov. 19, 2005 deaths.

Testifying under immunity, Laughner said Lt. Andrew Grayson told him to delete the photos so they would not be part of a statement being prepared for top-ranking officers and a Time magazine reporter. Laughner said he felt the order amounted to obstruction of justice but that he complied and later lied when asked whether any pictures had been taken.

Grayson, who has also been charged, faces a preliminary hearing on June 18.

"It was wrong," Laughner said. "Somebody was asking for them, and we're not going to give them to them? It's not right, but I didn't say anything."

Although Laughner deleted the pictures from his computer, the images remained on his digital camera and are now part of the biggest criminal case against U.S. troops in the war in Iraq.

Three enlisted Marines have been charged with murder.

Two dozen people were slain after a roadside bomb killed Lance Cpl. Miguel Terrazas, who was driving a Humvee. In the aftermath, Marines killed five young men outside their car and went house to house looking for insurgents.

The Marines have said they believed they were taking fire from the houses. They used fragmentation grenades and machine guns to clear the homes, but instead of hitting insurgents, they killed civilians.

Laughner arrived several hours after the roadside bomb. He said Staff Sgt. Frank Wuterich, who led the troops involved in the shootings, told him the men in the car had "engaged" the Marines with weapons, that Marines encountered an insurgent firing at them in one house and that weapons were found in the houses.

Laughner testified that when he went to the houses to look for evidence of insurgents, he instead found a wounded girl screaming hysterically. Through an interpreter, she said the Marines came into her house and killed her family, Laughner said.

Chessani's attorney said he did not attend Thursday's hearing and could not comment on Laughner's testimony.

At the end of Chessani's hearing, an investigating officer will make a recommendation about whether the charges should go to trial.