Ten days of testimony had focused on whether the relatively inexperienced armorer endangered fellow crew and cast members in her handling and supervision of firearms on the low-budget production set in New Mexico.
Judge Mary Marlowe Sommer ordered that Gutierrez be taken into custody immediately. She faces up to 18 months in state prison.
As deputies led her from the courtroom, Gutierrez told her distraught mother, "I'll be okay."
Jurors, who reached their decision in just three hours, acquitted Gutierrez on a second charge of evidence tampering.
Just after lunch on Oct. 21, 2021, Gutierrez mistakenly loaded a live round into a reproduction Colt .45 revolver that actor Alec Baldwin was using inside a movie-set church outside Santa Fe.
Baldwin cocked the gun, pointed it toward the camera and it fired one live bullet that killed cinematographer Halyna Hutchins and wounded director Joel Souza. Baldwin denies having pulled the trigger. His own manslaughter trial is set for July 10.
"This case is about constant, never-ending safety failures that resulted in the death of a human being and nearly killed another," said New Mexico state special prosecutor Kari Morrissey in her closing statements earlier Wednesday.
Gutierrez's lawyer Jason Bowles said he would appeal the decision.
"My sense was the evidence was insufficient and it was a lot of speculation," Bowles said outside the courthouse following the decision.
During the trial Bowles argued that the movie's production company tried to cut costs by employing Gutierrez as both a part-time armorer and a props assistant in the gun-heavy Western.
During the trial, movie-set firearms safety expert Bryan Carpenter testified that more armorers were needed on the set.
New Mexico's worker safety agency in 2022 fined the company, Rust Media Productions, the state's maximum possible penalty for ignoring industry firearm safety guidelines.
As one of the least experienced, least powerful people on set, lawyer Bowles said his client was taking the blame for management.
"You've got a convenient fall person, a convenient scapegoat," said Bowles.
'RUSSIAN ROULETTE'
Throughout the trial witnesses ranging from director Souza to assistant director Dave Halls said it was beyond anyone's imagination that live rounds could be mingled in with dummy rounds on the production.
State prosecutors and defense lawyers have fought over the source of live rounds, which are strictly forbidden on movie sets.
Juror Alberto Sanchez, a truck driver, said the jury of six women and six men believed Gutierrez brought the rounds on set.
"That was her job to check those rounds, those firearms," he told reporters after the verdict.
During the trial a Santa Fe detective cited "circumstantial evidence" that Gutierrez unknowingly brought the live rounds to "Rust" from a previous production in a white cardboard box.
Morrissey gave jurors photos taken up to 10 days before the shooting showing a live round in the box and one in Baldwin's bandolier.
"That's a mountain of circumstantial evidence," Morrissey said. "This was a game of Russian roulette every time an actor had a gun loaded with dummies."
Bowles repeatedly blamed props supplier Seth Kenney, who has not been charged, as the source of the live rounds. He said Kenney, a weapons consultant on movies like "Man Down" and a props supplier to "The Walking Dead," was not searched until a month after the shooting, allowing him to potentially dispose of evidence from his Albuquerque office.
Without knowing live rounds were on set, Bowles said Gutierrez did not show "willful disregard" for the safety of others, a requirement to convict her of involuntary manslaughter or a lesser charge of negligent use of a firearm, which carries up to six months in jail.
Half a dozen "Rust" crew members called by prosecutors testified that safety meetings were skipped, that Gutierrez sometimes failed to check whether weapons were loaded, and that Baldwin broke basic firearms safety rules.
