<p>AZ ZUBAYR, Iraq -- On March 22, a four-man television crew roaming the war zone alone drove rented SUVs onto a battlefield near here and into withering machine-gun fire during a confrontation between U.S. tanks and Iraqi soldiers.</p>
<p>One journalist escaped. One was killed. The mystery of what happened to the other two men has consumed their employer, Britain's Independent Television News Ltd., ever since. Other reporters who happened on the scene soon afterward were barred by U.S. Marines from checking for survivors in the wrecked sport-utility vehicles, which had been labeled "TV" in large letters.</p>