Actor Alec Baldwin. [Source: Reuters]

Actor Alec Baldwin entered a not guilty plea on Thursday.

This is to a charge of involuntary manslaughter over the fatal shooting of cinematographer Halyna Hutchins on the New Mexico set of the Western film “Rust” in 2021, court documents show.

Baldwin made the plea while waiving a Feb. 24 court appearance that was set to be his first in the case on how live ammunition got mixed with dummy rounds on a Santa Fe film set, then went undetected.

New Mexico First Judicial District Attorney Mary Carmack-Altwies in January charged Baldwin and the movie’s set armourer, Hannah Gutierrez-Reed, with two counts of involuntary manslaughter for alleged “reckless” disregard for safety prior to Hutchins’ death.

Prosecutors last week downgraded charges against Gutierrez-Reed and Baldwin, reducing the possible prison time for the actor who fired a live round that killed Hutchins and wounded director Joel Souza while rehearsing a scene in front of the camera.

Baldwin’s defence team argued that he had been charged retroactively with a New Mexico firearms law that was passed after the shooting took place on Oct. 21, 2021.

The “30-Rock” actor has said he is not responsible for Hutchins’ death, arguing that Gutierrez-Reed failed to check rounds she loaded into his revolver and assistant director Dave Halls falsely told him it was a “cold gun” – an industry term meaning it was unloaded or contained only dummy rounds.

Gutierrez-Reed will make a first court appearance on Friday via video link, her lawyer Jason Bowles said.

She has blamed the shooting on potential sabotage, Baldwin’s lack of firearms training and a failure by Halls and Baldwin to call her onto set for extra firearm checks.

Santa Fe County Sheriff’s Office, the lead investigator on the case, and prosecutors have yet to present evidence on the source of six live long Colt .45-caliber rounds found on the set, including the bullet that killed Hutchins.

Halls also pleaded not guilty in a Thursday court filing in which he waived a Feb. 24 first court appearance. He has entered a plea deal for misdemeanour charges and has been called as a witness by prosecutors should the case reach trial.

Baldwin and Gutierrez-Reed now face a maximum of 18 months in prison if convicted. Before the prosecutor dropped the alternative charge they risked a minimum five years in jail.