SANTA FE (REUTERS, BLOOMBERG) - A .45-caliber Colt revolver used on the set of the film Rust was not thoroughly checked before being given to actor Alec Baldwin, who fired a live lead bullet in an accidental fatal shooting last week in New Mexico, according to officials and a new court filing.

New details about the incident emerged on Wednesday (Oct 27) during a news conference by Santa Fe County Sheriff Adan Mendoza and District Attorney Mary Carmack-Altwies and in an affidavit filed by the sheriff's department.

Mr Mendoza told reporters there was a complacent attitude toward safety on the set before last Thursday's shooting that killed cinematographer Halyna Hutchins during a rehearsal.

The authorities are asking the FBI to analyse the bullet fired by Baldwin, according to a Bloomberg report.

Ms Hannah Gutierrez, the crew member in charge of weapons on the set, told investigators she had checked guns there but found no "hot rounds" - apparently meaning live ammunition - before the shooting, according to the affidavit.

Mr Dave Halls, the film's assistant director, handed the gun to Baldwin, telling the actor it was "cold" or safe.

"He advised he should have checked all of them, but didn't," Mr Halls told police, according to the affidavit. Halls was referring to the barrels of the revolver.

Mr Halls had been fired from a previous movie set in 2019 over a mishap with a gun, production company Rocket Soul said on Monday. He has made no public comment on the incident.

Legal experts have said that criminal charges are possible but not likely against Baldwin.

He and the other producers of the film have hired the law firm Jenner & Block to investigate the accident.

In a letter sent to cast and crew on Tuesday night and seen by Reuters, the Rust production team said the law firm "will have full discretion about who to interview and any conclusions they draw".