An FBI forensic report has concluded that the gun used in the fatal shooting on the “Rust” movie set last year could not have been fired without pulling the trigger.

Actor Alec Baldwin fired the shot that killed cinematographer Halyna Hutchins during rehearsals for the Western, as CrimeOnline previously reported. Baldwin believed the gun he was handling was “cold” — meaning it didn’t have live ammunition.

Baldwin, also the producer of the film, previously said he didn’t believe he had pulled the trigger and that the gun went off in his hand, striking Hutchins in the chest and wounding director Joel Souza.

ABC News obtained a copy of the FBI report on Friday and agents determined that the .45 Colt could “could not be made to fire without a pull of the trigger” from the quarter-, half-, or full-cocked positions. The gun could detonate a primer “without a pull of the trigger when the hammer was struck directly” from a de-cocked position, the report said, normal behavior for the weapon.

The Santa Fe County Sheriff’s Office, which is leading the investigation into the shooting, said it received the report and other FBI documents earlier this month. Those documents were reviewed by the New Mexico Office of the Medical Investigator,” which classified Hutchins’ death as an accident, ABC said.

“Death was caused by a gunshot wound of the chest. Review of available law enforcement reports showed no compelling demonstration that the firearm was intentionally loaded with live ammunition on set,” the postmortem report stated. “Based on all available information, including the absence of obvious intent to cause harm or death, the manner of death is best classified as accident.”

The Santa Fe County District Attorney has not yet filed any charges, and the sheriff’s office said it was awaiting phone records from Baldwin. The district attorney’s office said in January that it had the actor’s cell phone.

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[Featured image: Alec Baldwin/AP Photo/Seth Wenig, File and Halyna Hutchins/Instagram]