Army Pfc. Lance Aviles, present at the mass slayings, said he was directed to delete his videos of the scene by superior officers, the Austin (Texas) American-Statesman reported Monday.
Aviles was awaiting medical processing before deploying to Afghanistan.
He did not say who those officers were or why they wanted him to erase the images captured at the 467th Medical Detachment, the newspaper said.
There have been 29 witnesses during the last three days of the Article 32 pretrial hearing before Col. James Pohl, who will determine if Hasan will stand court-martial for allegedly shooting to death 13 and wounding 32 at the military base Nov. 5.