The scene in Fallujah was unforgettable: four Americans shot, their bodies defiled, two of them hung from a bridge.

During his 20 years in the service, Wesley Batalona built skills that would come into play later.

A 1995 tour in Bosnia steered Jerry Zovko to the business that would take him to Iraq.

Erik Prince thought he saw an opportunity as the U.S. military began to shrink. He was right.

People who knew Scott Helvenston struggle to explain how strong he was.

The ambush was so sudden that the four private contractors had little chance to react.

Little has been done to determine the facts of the ambush.

Even as Secretary of State Condoleezza Rice defended her department's oversight of private security contractors, evidence surfaced Thursday that the U.S. sought to conceal details of Blackwater shootings of Iraqi civilians more than two years ago.

A State Department official resigns a day after a report of lapses in oversight of guards.

Heavier guns and sturdier trucks would not have saved a team of Blackwater USA guards brutally killed in March 2004 after being lured into an ambush, the embattled private security contractor reports.

The congressman leading an investigation into Blackwater USA says that the embattled security company may have evaded tens of millions of dollars in federal taxes and was seeking to hide its tax practices.

Democratic congressman accuses the security contractor of attempting to spirit away Iraqi aircraft.

The behavior of private security contractors in Iraq is in direct conflict with the goals of the U.S. military, Defense Secretary Robert M. Gates said Thursday.

The chief executive of Blackwater USA, whose guards are accused of killing 17 Iraqis in Baghdad last month, says he welcomes the FBI investigation into the shooting and supports the prosecution of any bad acts.

Blackwater USA has ended an inquiry into its performance by withdrawing from an industry group that initiated the review after the private security contractor's guards were accused of killing 17 Iraqis in Baghdad last month.