London ? A coroner ruled Friday that U.S. forces in Iraq unlawfully killed a British television journalist by shooting him in the head as he lay in the back of a makeshift ambulance during the opening days of the war.

The widow of reporter Terry Lloyd called for the perpetrators to be prosecuted for the “despicable, deliberate, vengeful act.” And Deputy Coroner Andrew Walker said he would ask the attorney general to take steps to bring to justice those responsible for the death.

But prosecution of U.S. service members seemed unlikely.

Lt. Col. Mark Ballesteros, a Pentagon spokesman, said an investigation into the killing of Lloyd, 50, a veteran reporter for the British TV network ITN, was completed in May 2003 and “determined that U.S. forces followed the applicable rules of engagement.”

The coroner inquest was unable to determine whether the bullets that killed Lloyd on March 22, 2003, in southern Iraq were fired by U.S. ground forces or helicopters.