Investigators looking into the fatal shooting on the set of Alec Baldwin's film Rust, say there was "some complacency" around safety.
Presenting their initial findings on Thursday's shooting, officials said they believe actor Alec Baldwin was handed a gun loaded with a live round during a rehearsal.
It also emerged that the .45-caliber Colt – which has been described by law enforcement as a “legit” antique gun, not a prop gun – was not thoroughly checked before being given to Baldwin.
The US actor then accidentally shot dead cinematographer Halyna Hutchins and wounded the film's director Joel Souza.
Baldwin, who had been pointing the gun at the camera, was told by crew that the gun was “a cold gun”, meaning the gun contained no ammunition and was safe to use.
Prosecutors are refusing to rule out filing criminal charges over the case.
Santa Fe district attorney Mary Carmack-Altwies told reporters that "all options are on the table at this point" as their investigation continues.
According to that affidavit, the film’s assistant director Dave Halls admitted to investigators that he “should have checked all” the rounds in the gun before handing it to Baldwin but had not done so.
The gun was also handled by armorer Hannah Gutierrez-Reed before Baldwin fired it.
Gutierrez-Reed, who was in charge of weapons on the set, told investigators that she had checked guns there but found no “hot rounds” – meaning live ammunition – before the shooting, according to a new affidavit filed by the sheriff’s department on Wednesday.
Further concerns were raised about Halls on Monday, after a producer who communicated with the Associated Press said he [Halls] had been fired from a previous job after a gun went off on a film set and wounded a member of the crew.
No decisions have been made yet about any criminal charges.
“We believe that we have, in our possession, the firearm that was fired by Mr Baldwin. This is the firearm we believe discharged the bullet,” said Santa Fe’s county sheriff, Adan Mendoza at Wednesday’s press conference.
Approximately 600 pieces of evidence have been recovered so far - including three firearms and 500 rounds of ammunition.
Mr Mendoza, said the ammunition trove constitutes "a mix of blanks, dummy rounds and what we are suspecting is live rounds" that require lab analysis.
A "lead projectile" was also recovered from the shoulder of wounded director Joel Souza and handed over as evidence.
Possible additional live rounds, including the bullet the authorities believe killed Hutchins, will be submitted to the FBI crime lab in Quantico, Virginia, confirmed the sheriff.
He refused to speculate, when questioned by reporters, about what happened to result in a single bullet killing one and then injuring another person.
Mendoza said more interviews still needed to be conducted, including an additional interview with Baldwin, whom the sheriff described as “cooperative”.
The actor was also a producer on the movie, where filming was shut down and has not resumed since Hutchins’ death.
Mendoza also confirmed that his office was investigating reports of informal incidents of target practice having taken place on or near the set before the incident, and rumors of crew members drinking the night before.
There are also reports that just hours before the fatal shooting, several crew members had walked out, unhappy about pay and working conditions as well as safety fears, court papers said.
“I think the industry has had a record recently of being safe. I think there was some complacency on this set. And I think there are some safety issues that need to be addressed by the industry and possibly by the state of New Mexico,” Mendoza said.