A New Mexico judge denied a request Friday to use immunity to compel a movie set armorer to testify at actor Alec Baldwin’s involuntary manslaughter trial for the fatal shooting of a cinematographer on a movie set for the Western film “Rust.”

Earlier this year, armorer Hannah Gutierrez-Reed was convicted of involuntary manslaughter and sentenced to 18 months in prison for her part in the 2021 shooting death of Halyna Hutchins. Her statements to investigators and workplace safety regulators are expected to weigh heavily in Mr. Baldwin’s trial.

Judge Mary Marlowe Sommer rejected the prosecution’s motion to force Ms. Gutierrez-Reed’s testimony after learning that she intended to invoke her Fifth Amendment right if called to the stand. The judge said other witnesses could fill in most of the gaps.

“It’s pretty clear that she does not intend to cooperate,” Ms. Marlowe Sommer said after hearing arguments from both sides. “I haven’t heard of anything that she might testify to that someone else could not testify to.”

The judge acknowledged that Ms. Gutierrez-Reed could offer new testimony concerning gun safety training and whether or not Mr. Baldwin had fully participated.

Special prosecutor Kari Morrissey indicated that the state would still consider calling on Ms. Gutierrez-Reed to testify without immunity at Mr. Baldwin’s trial, which is scheduled to begin July 10.

Mr. Baldwin has not supported efforts to force her testimony.

Gun safety protocols and Mr. Baldwin’s authority as a co-producer and lead actor in the film played prominently in Ms. Gutierrez-Reed’s trial in March.

Ms. Gutierrez-Reed, who was acquitted of tampering with evidence, is appealing her conviction of involuntary manslaughter. She is also facing a separate charge for carrying a gun into a bar in Santa Fe just weeks before the fatal shooting.

An attorney for Ms. Gutierrez-Reed argued that compelling her to testify, even with immunity, would “virtually eliminate” her chance of a fair trial on the pending charge and could disrupt the motion to appeal her conviction.

Hannah Gutierrez-Reed, the former armorer for the movie "Rust," listens to closing arguments in her trial at the district court in Santa Fe, N.M., on March 6, 2024. (Luis Sánchez Saturno/Santa Fe New Mexican via AP)

Also, during Friday’s hearing, the judge ruled against Mr. Baldwin’s attorneys’ request to scuttle the trial. They argued that Mr. Baldwin had no reason to believe the firearm could contain live ammunition, making him unaware of the risks.

The court will hear a second motion to dismiss the case based on the argument that the FBI heavily damaged the gun during forensic testing before it could be examined for possible modifications that might exonerate the actor.

“The government took the most critical evidence in this case—the firearm—and destroyed it by repeatedly and pointlessly striking it with a mallet,” wrote defense attorneys in the court filings. “Government agents knew that the firearm would not survive.”

On Oct. 21, 2021, Mr. Baldwin, 66, was allegedly pointing the gun at Mrs. Hutchins during rehearsal when it fired, killing her and wounding director Joel Souza. Mr. Baldwin claims the gun discharged without him pulling the trigger, although he admits he pulled back the hammer.

Prosecutors are expected to present evidence that shows the gun was working properly before the shooting and “could not have fired absent a pull of the trigger.”

Lucien Haag, forensic science firearms evidence examination and shooting reconstruction expert witness, shows the jury a gun exactly like the evidence gun during the involuntary manslaughter trial of Hannah Gutierrez-Reed at the First Judicial District Courthouse in Santa Fe, N.M., on Feb. 27, 2024. (Sánchez Saturno-Pool/Getty Images)

An FBI expert testified at Ms. Gutierrez-Reed’s trial, stating that the gun was fully functional with safety features when it arrived at an FBI laboratory for testing. He said he had to strike the fully cocked gun with a mallet and break it to make the weapon fire without pulling the trigger.

Mr. Baldwin has pleaded not guilty to the involuntary manslaughter charge, which carries a maximum sentence of 18 months in prison.

Judge Marlowe Sommer previously rejected another motion for dismissal of the charge against Mr. Baldwin, ruling that the grand jury was able to make an independent judgment on the indictment.

Last year, special prosecutors previously dismissed an involuntary manslaughter charge against the actor, saying the weapon may have malfunctioned due to a possible modification. But later, they reversed their decision after a new analysis of the gun showed it was fully operational. They successfully pursued a grand jury indictment.

The Associated Press contributed to this report.