Alec Baldwin
Alec BaldwinReuters/Dennis Van Tine/ABACAPRESS.COM

The criminal investigation into the fatal shooting on a US movie starring Alec Baldwin is "nearing completion," the officer leading the probe said Tuesday, according to the AFP news agency.

Santa Fe Sheriff Adan Mendoza's comments come as his department released a trove of materials around the incident that claimed Halyna Hutchins' life on the set of low-budget Western "Rust," including footage of Baldwin apparently practicing with the gun that killed her.

"We've estimated a time weeks and not months," Mendoza was quoted as having told broadcaster ABC.

"There's a few things that we're waiting for in the final FBI report in regards to the analysis of the firearm, the munitions, the latent prints and DNA. We're also waiting on the office of the medical investigator to complete their report and analysis of a little bit more cell phone data."

Baldwin was holding a Colt gun during a rehearsal for the Western in New Mexico in October when it discharged a live round, hitting cinematographer Halyna Hutchins and director Joel Souza. Hutchins later died in hospital of her wounds.

Baldwin, who was a producer as well as the star of the movie, had been told the gun was safe and has previously said he did not pull the trigger.

Footage released by the sheriff's department show first responders rushing to treat Hutchins, as well as a dazed Baldwin's first encounters with law enforcement.

Baldwin has been named as a defendant in several civil lawsuits, including one from the husband of Hutchins.

The actor’s lawyers argue that his "Rust" movie contract protects him from financial liability in the fatal shooting.

Strict measures are supposed to be in place on movie sets to prevent tragedies, including the exclusive use of dummy or blank rounds in any production involving firearms.

But a health and safety probe by New Mexico officials, which levied a fine of over $136,000, said last week that producers had shown "plain indifference" to these protocols.

Mendoza said Tuesday the provenance of the live round that killed Hutchins was "one of the key questions" of the criminal probe.

"Nobody's come forward and admitted to bringing ammunition to the set," he said, according to AFP.

Mendoza said no decision had yet been taken on whether Baldwin would face criminal charges.

"He was the one that handled the weapon that fired the round that that led to the fatality and the injury," he said.

"We're going to work in conjunction with the (district attorney's) office to determine if there is criminal neglect or criminal charges."

The actor has said that he had no idea how a live bullet got onto the set.

"Someone is responsible for what happened, and I can’t say who that is, but it’s not me," Baldwin said in an interview following the incident, adding, "Honest to god, if I felt I was responsible, I might have killed myself."