LOS ANGELES (AFP) - The woman in charge of the gun fatally fired by actor Alec Baldwin on the set of Rust told police she "didn't really check it too much" immediately before the tragedy.

Ms Hannah Gutierrez-Reed, armourer on the low-budget Western, spoke to investigators as they probed how live rounds ended up on the New Mexico film set in October, leading to the death of cinematographer Halyna Hutchins.

Hutchins, 42, was shot and killed as Baldwin rehearsed a scene in which he fires a gun at the camera.

According to an affidavit released on Tuesday (Nov 30), Ms Gutierrez-Reed told police she had loaded the Colt .45 with five dummy rounds before a lunch break.

After lunch, the weapon was retrieved from a safe and she added a final round before handing it to another crew member. Moments later, she heard a gun shot from inside the set.

Ms Gutierrez-Reed said she "didn't really check it too much" because the weapon had been locked up at lunch.

"We had the gun the whole time before that, and nothing happened, and I wasn't in there, and they weren't even supposed to be pulling the hammer back," she added.

Police seized more than 500 rounds of ammunition from the set, which they believed to be a mix of blanks, dummy rounds and some suspected live ammunition.

On Tuesday, investigators shared new information about the possible origin of live rounds.

Ammunition for the production came from multiple sources, including Mr Seth Kenney, an Arizona weapon rental supplier.

Mr Kenney told investigators he may have passed "reloaded ammunition" to the Rust set which matched the logo on a cartridge suspected to have contained the live round that killed Halyna.

"Reloaded ammunition" refers to rounds that are assembled from component parts, not manufactured as complete live rounds.

Ms Gutierrez-Reed's father Thell Reed, a veteran armourer, said he had provided live ammo to Mr Kenney on a previous film they worked on together that was "not factory made", and which was never returned.

Prosecutors have refused to rule out criminal charges against any person involved with Rust, including Baldwin and Ms Gutierrez-Reed.

The pair are also among those named in at least two civil lawsuits filed by other crew members.

Ms Gutierrez-Reed has said she has "no idea" why live rounds were present, and her lawyers suggested an act of "sabotage" by disgruntled crew members may have caused the tragic shooting.

Reports have emerged of disquiet among staff over allegedly lax safety procedures, and Santa Fe Sheriff Adan Mendoza has spoken of "complacency" on the New Mexico set.

But Baldwin, 63, has called the tragedy a "one in a trillion episode" and insisted Rust had a "well-oiled crew".