"Did I see Jayson pull the trigger?" Benoit Benjamin responded to a question by defense lawyer Billy Martin. "Yes, I saw him pull the trigger."
A day earlier, Benjamin had said only that Williams' finger was near the trigger.
The exchange came after Martin insisted that Benjamin hold the shotgun and demonstrate, as he had on Wednesday, how Williams handled the weapon. On both days, Benjamin held the weapon in one hand with the shotgun open and then raised his forearm, snapping the weapon shut at waist-height.
Later Thursday, Martin used another prosecution witness and former teammate from the New Jersey Nets, Christopher Morris, in an attempt to discredit aspects of Benjamin's testimony.
Even so, Morris became the fourth witness to testify that Williams wiped down the gun after the shooting and tried to put it in the hands of the stricken driver, Costas "Gus" Christofi.
At the time of the shooting in February 2002, Williams had retired and Benjamin and Morris were playing for the Harlem Globetrotters. They testified with immunity from prosecution after admitting they lied in initial statements to police.
The trial resumes Monday.
The defense maintains the shooting was an accident, but Morris and Benjamin gave testimony that supported prosecution efforts to show that Williams handled the weapon recklessly, then tried to make the shooting look like a suicide and persuade others to lie.
Williams, 36, faces charges including aggravated manslaughter and witness tampering that could carry up to 55 years in prison. The least of the charges carries a penalty of up to 18 months in prison, but would likely result in probation.