But from the witness stand in the Blackwater criminal trial this week, Murphy testified that he saw Slough fire at least two grenades into a car where a woman and her son died, two of 14 Iraqis killed on Sept. 16, 2007, in a downtown Baghdad square.

In three days of testimony, Murphy became the first Blackwater security guard to testify against his former associates in a trial expected to take months.

Slough is charged with manslaughter, attempted manslaughter and violating gun laws, as are two other defendants, Dustin Heard and Evan Liberty. A fourth defendant, Nicholas Slatten, is charged with first-degree murder in the death of the driver of the car. All four have pleaded not guilty.