SANTA FE, Oct 26 — Authorities investigating the movie-set shooting by Alec Baldwin will ask for a ballistics analysis they hope will help answer the key question of what type of material was discharged from the gun that killed a cinematographer.

Investigators have spoken with the person in charge of weapons on the set, known as an armorer, and are conducting additional interviews with potential witnesses, Juan Rios, spokesman for the Santa Fe Sheriff’s Department, said yesterday.

One of the central mysteries remains what kind of projectile was fired from the gun and how it got there. Investigators hope a forensic analysis of ballistic evidence will shed light on those questions, he said.

"This is a complicated case,” he said.

Cinematographer Halyna Hutchins, 42, was killed and director Joel Souza, 48, was injured when a revolver that Baldwin was using during rehearsal discharged. The actor had been told that the gun was not loaded, according to court documents.

The accident happened on the set of the Western indie movie Rust at Bonanza Creek Ranch near Santa Fe on Thursday.

Rios said investigators had interviewed armorer Hannah Gutierrez, 24, who was responsible for the safety of weapons on the set, but gave no details. Gutierrez has not spoken publicly, and Reuters has not been able to reach her.

Baldwin, the director and others have also been interviewed but no charges have been brought.

Before the incident, camera operators had walked off the set to protest working conditions, according to a sheriff’s department affidavit. The probe into the shooting is examining information beyond just what happened that day, Rios said.

Investigators "are looking at everything that should have been followed, and safety standards on down,” Rios said.

The Santa Fe County Sheriff and the local district attorney are scheduled to speak about the case at a news conference on Wednesday. Rios said it would take time for investigators to draw conclusions about what happened.

In her first public statements about the incident, Baldwin’s wife, Hilaria, said yesterday that "it’s impossible to express the shock and heartache of such a tragic accident.”

"My heart is with Halyna. Her husband. Her son. Their family and loved ones. And my Alec,” she wrote on Instagram. — Reuters