When Alec Baldwin set out to make the western Rust in 2021, it was a passion project for the veteran actor. He co-created the story, served as a producer and starred as the film’s lead Harland Rust, an outlaw with a bounty on his head.

Nearly three years on, the 66-year-old had assumed the role of criminal defendant, standing trial in New Mexico for involuntary manslaughter in the death of the cinematographer Halyna Hutchins during a rehearsal on the film’s set.

As Baldwin entered a Santa Fe courtroom on Wednesday, the day the trial began, he was staring down the prospect of 18 months in prison. By the week’s end, in a dramatic twist fit for a Hollywood drama, he was walking out a free man after a judge found the prosecution and law enforcement had intentionally withheld evidence in the case that could have been favorable to the actor.

The prosecution’s case fell apart in a matter of hours on Friday. A witness testified that Kari Morrissey, a special prosecutor leading the state’s case against Baldwin, was directly involved in a decision to keep potential crucial evidence separate from the Rust case. Another special prosecutor suddenly resigned in the middle of the day, and Morrissey called herself to the stand as a witness.

By the day’s end, Judge Mary Marlowe Sommer had found the state withheld information in a manner that was “intentional and deliberate”. Baldwin wept. Hilaria Baldwin, his wife, covered her face and then hugged his attorneys.

It was a shocking end to a high-stakes case that has been closely watched by the film industry and documented by dozens of journalists from outlets around the world.

The swift unravelling surprised even seasoned legal observers. “It was stunning to see the prosecution fall apart so quickly. One of the special prosecutors bolted before the judge could even make her decision,” said Neama Rahmani, a former federal prosecutor and president of Los Angeles-based West Coast Trial Lawyers.

“It’s one of the most botched prosecutions in American history. It should be taught in school as an example of how not to bring a case.”

Astonishing courtroom scenes end a tense week

Friday’s remarkable turn of events capped a trial that had all the makings of a film script – a star accused of acting recklessly with a firearm on set and causing the death of a crew member, a famous audience in the form of Baldwin’s actor brother and influencer wife, near-constant battles between the prosecution and defense and grueling cross-examinations.

Over the last week, a bespectacled and stooped Baldwin shuffled into a Santa Fe courthouse each day with his wife and sat alongside his high-profile legal team for proceedings that were livestreamed and viewed across the world.

The potential repercussions for Baldwin had been very real – being found criminally liable for causing the death of 42-year-old Hutchins and up to 18 months in prison – and a guilty verdict would have had lasting effects in the film industry.

A jury was seated on Tuesday and proceedings kicked off on Wednesday. As things got under way inside the courtroom, the prosecution and defense offered very different versions of the events that unfolded on 21 October 2021.

The Rust crew was rehearsing at the Bonanza Creek Ranch, a popular movie set about 30 minutes from Santa Fe, when a gun Baldwin was holding fired a single round of live ammunition, striking Hutchins and the director, Joel Souza.

The bullet entered underneath Hutchins’ right underarm and perforated her right lung before traveling through the spine and lacerating her spinal cord, the prosecution told the jury in opening statements. Hutchins, who was a rising star in the industry, was transported via helicopter to a nearby hospital, where she died.

The aftermath was captured via body-camera from a New Mexico sheriff’s deputy who responded to the incident and testified in court this week. The footage showed medics’ desperate effort to save Hutchins, who was lying on the floor with her arm over her face.

In the view of the prosecution, Baldwin was a reckless and arrogant actor who flagrantly and repeatedly mishandled firearms on set. He broke the “cardinal rules of firearm safety” by leaving his finger on the hammer and trigger, and pointing it at people on set while filming.

The defense countered by portraying Baldwin as an actor who was focused on doing his job and arguing that he was failed by the crew members who were responsible for overseeing weapons and safety on set. The attorney Alex Spiro emphasized that Baldwin had been told the gun was safe moments before it was handed to him.

It all appeared to be setting up days of tense exchanges over whether Baldwin was at fault, with the actor himself expected to possibly take the stand. But ultimately, the jury was unable to render a verdict on the question after things swiftly deteriorated on Friday, when previously unseen evidence was presented.

The court was facing a potentially compelling day as prosecutors were expected to call Hannah Gutierrez-Reed, the film’s armorer who was found guilty of involuntary manslaughter earlier this year, to the stand.

But on Friday morning, the defense alleged the state had withheld evidence and asked the judge to dismiss the case. Shortly after, Sommer dismissed the jury – setting off a day of gripping testimony and astonishing courtroom exchanges.

Things fall apart

Issues first emerged on Thursday, when Baldwin’s defense said that the state had received evidence related to how live rounds of ammunition ended up on the set of Rust. Prosecutors have long said that Gutierrez-Reed was the source of the live round, but the new evidence reportedly called that into question.

A “good samaritan”, Troy Teske, had come forward to police this year with a box of munitions that he claimed came from the prop supplier, Seth Kenney, and matched the ammunition that killed Hutchins, Spiro told the court.

The state did not include the report of an interview with Teske with the other Rust evidence. Nor did they share it with Gutierrez-Reed’s lawyer, Spiro said.

Morrissey had said that the ammunition brought forward did not match the ones on the Rust set: “This has no evidentiary value whatsoever.”

The judge asked to see the report and the evidence, a box of ammunition. Moments later, Sommer, who was wearing gloves, stepped down from the bench to examine evidence directly and found that some of the bullets did in fact resemble those from Rust.

At one point while questioning a witness, Morrissey grabbed a bullet and handled it herself – without gloves, drawing an objection from the defense.

Alexandria Hancock, with the Santa Fe county sheriff’s office, testified on Friday that she and other officials made the decision to file it separately from the other Rust evidence in an entirely different case file because they had not yet established it was connected to the case, she said.

Morrissey said several times that Troy Teske, the man who came forward with the ammunition, was a friend of Gutierrez-Reed’s father. She said she had never seen the evidence until Friday morning. But as the judge questioned Hancock, she said that Morrissey was directly involved in the decision to keep the evidence separate from the Rust case. The audience in the courtroom audibly gasped.

Morrissey appeared determined to defend her name and by the end of the day, in what looked like a hail Mary, she called herself to the stand, despite the judge telling her that was unnecessary. “You don’t have to say anything under oath if you don’t want to,” Sommer said.

Morrissey testified that she was not aware that the evidence brought forward would not be linked to the Rust case number.

She countered Spiro’s suggestion that she didn’t like Baldwin. “I actually really appreciate Mr Baldwin’s movies,” she said. “I really appreciated the acting he did on Saturday Night Live.”

Spiro wasn’t done. In the final moments Morrissey was on the stand, he asked if she had ever referred to the actor as an “arrogant prick” and “cocksucker” in a conversation with a witness.

She said she did not recall doing so.

Baldwin, who had appeared tense during the week, looked increasingly heartened as the day went on. When the judge threw out the case, he wept and covered his face.

What happens next?

The judge dismissed the case with “prejudice”, putting a sudden end to the involuntary manslaughter case against Baldwin. The decision means that prosecutors cannot bring the same case against him again and, in all likelihood, Baldwin is off the hook for good.

The state’s conduct amounted to a “constitutional violation”,Rahmani said. He called it “the cardinal sin for a prosecutor”.

The ruling could also have major implications for Gutierrez-Reed, the film’s armorer, who could attempt to undo her conviction based on Friday’s decision.

“Not only is Baldwin a free man and he can’t be retried, but the Gutierrez-Reed conviction will likely be reversed,” Rahmani said.

Carl Tobias, of the University of Richmond law school, agreed that her defense would likely use the same approach as Baldwin’s lawyers.

“Hannah Gutierrez-Reed may attempt to make similar arguments to those that Baldwin and his counsel made and that her conviction should be overturned or at least conduct a retrial and that she be released from jail,” Tobias said.

The attorney for Matthew Hutchins, Halyna’s husband, said in a statement that he respected the court’s decision.

“We look forward to presenting all the evidence to a jury and holding Mr Baldwin accountable for his actions in the senseless death of Halyna Hutchins,” Brian J Panish said.