There is the question if it was a set up for a murder, as of course LE must consider, especially with the disagreements earlier in the day when people quit and were replaced with non union workers, which obviously was stressful, judging by Souza's own account in the affidavit.
ETA someone put a live round in the gun, for whatever reason, we don't know.
From the NYT link:
Mr. Souza was grappling with delays the day of the shooting, after about six members of the camera crew had quit over late pay and safety conditions, the affidavit said. Another crew had quickly been hired, but the production was off to a late start because of the labor problems. Mr. Souza said only one camera was available for recording before the shooting.
Asked about “the employees’ behavior,” Mr. Souza told investigators that “everyone was getting along” and that there had been “no altercations” to his knowledge.
The affidavit also includes notes from an interview with Reid Russell, a cameraman who was standing near Ms. Hutchins and Mr. Souza when the gun discharged.
Mr. Russell told the detective that after returning to the set from lunch, he had stepped outside for about five minutes; when he returned, according to the affidavit, Mr. Baldwin, Ms. Hutchins and Mr. Souza were setting up the scene and were already “in possession of the firearm.” Mr. Russell said he was not sure if the firearm had been inspected because he had been absent for those five minutes.
