5 biggest mysteries still surrounding the 'Rust' movie-set shooting involving Alec Baldwin

Six weeks after a fatal shooting on a New Mexico movie set, there are still more questions than answers about how such a tragedy could happen.

On Oct. 21, Alec Baldwin was nearing the end of the 21-day shoot of "Rust," an independent Western drama that he was producing and starring in. The actor was rehearsing with a prop gun that he was told did not contain live ammunition when the weapon went off, killing cinematographer Halyna Hutchins and injuring director Joel Souza.

With the investigation ongoing, and renewed conversation about safety on movie sets, here's what is still unknown about the case.

Alec Baldwin: As 'Rust' star faces a lawsuit, all eyes are on the gun that killed Halyna Hutchins

1. How did the gun go off if Alec Baldwin 'didn't pull the trigger'?

Baldwin sat down with George Stephanopoulos to talk about the shooting in an hourlong ABC special (8 p.m. EST/PST Thursday, streaming on Hulu after). In the interview, Baldwin tears up as he talks about Hutchins. He is emphatic that he "didn't pull the trigger."

“I would never point a gun at anyone and pull a trigger at them. Never," Baldwin tells Stephanopoulos, acknowledging he has "no idea" how a live bullet got on the set. "Someone put a live bullet in a gun, a bullet that wasn’t even supposed to be on the property."

In the scene being rehearsed, "I would have cocked the gun, and I said, ‘Do you want to see that?' " Hutchins told him yes and instructed him to "tilt it down a little bit," he said. "I cock the gun and I go, ‘Can you see that?' ... And I let go of the hammer of the gun and the gun goes off."

Affidavits released by investigators state that “the prop gun was fired by the Actor Alec Baldwin.”

Lisa Torraco, assistant director Dave Halls' attorney, backed up Baldwin's claims this week, telling ABC that the actor's finger "was never in the trigger guard." But Santa Fe County Sheriff Adan Mendoza told Fox News, "Guns don't just go off. So whatever needs to happen to manipulate the firearm, he did that and it was in his hands."

Guns can be unintentionally discharged because of mechanical malfunction or insufficient firearm training and handling.

'Rust' shooting: Affidavit reveals new details about source of live ammunition in Alec Baldwin's gun

2. Why were live rounds of ammunition on the 'Rust' set?

Mendoza revealed that more than 500 rounds of ammunition were discovered on the film's set in New Mexico, which included a mix of blanks, dummy rounds and suspected live rounds. Investigators also uncovered three firearms: a plastic gun, a modified revolver and the working gun that Baldwin discharged.

It's still unclear how or why there was live ammunition in the gun, and what the composition of the bullet was that is believed to have killed Hutchins and struck Souza.

Earlier this week, the sheriff's office issued a warrant to search PDQ Arm & Prop, which supplied the guns and ammo to "Rust." An affidavit included with the warrant says Seth Kenney, the owner of PDQ, told investigators on Oct. 29 that the live round shot from Baldwin's prop gun may have been "reloaded ammunition" bearing the logo of Starline Brass, the company that manufactures the dummy rounds and blanks his business supplies to movie sets.

Prop master Sarah Zachry told investigators days earlier that "Rust" got its ammunition from multiple sources, including Kenney and set armorer Hannah Gutierrez-Reed, who brought rounds from a production she worked on previously.

But Kenney told "Good Morning America" on Thursday that "it's not a possibility" the live ammunition came from PDQ or from him.

"When we send dummy rounds out, they get individually rattle tested before they get sent out," he said, with a rattling sound signifying dummy ammunition. "So if you have a box of 50, you've got to do it 50 times. And then you know they're safe to send."

The presence of live ammunition has also sparked a bigger discussion about why real guns are used on sets in the first place, with A-listers including Dwayne Johnson pledging to use rubber guns on projects going forward.

'I didn't pull the trigger': Alec Baldwin gives first interview since fatal 'Rust' shooting

3. How long was the gun that killed Halyna Hutchins left unattended?

Before a lunch break on the day of the shooting, Gutierrez-Reed loaded the gun with five rounds of ammunition from a prop box labeled "dummies," and the firearm was stored in a safe, according to an affidavit released Tuesday. After lunch, the gun was retrieved from the safe and she loaded it with one more round.

Her attorneys, Jason Bowles and Robert Gorence, initially said that the prop guns had been left unattended for about two hours. "Was there a duty to safeguard (the guns) 24/7?" Gorence said. "The answer is no, because there were no live rounds."

But after consulting Gutierrez-Reed, the lawyers later said they had been mistaken, and the guns were actually locked in a safe in a prop truck and left unattended for no more than five or 10 minutes.

Gutierrez-Reed released a statement through her lawyers last month, saying that she has "no idea where the live rounds came from." Speaking to "Today" anchor Savannah Guthrie, Bowles said he believes that a third party may have put a live round of ammunition in the prop box, after several crew members reportedly walked off set the morning of the shooting in protest of safety conditions.

“I believe that somebody who would do that would want to sabotage the set, want to prove a point, want to say that they’re disgruntled, they’re unhappy,” Bowles said. "I think you can't rule out anybody (in the crew) at this point."

In response to the search warrant, Bowles told USA TODAY in a statement Tuesday that it's "a huge step forward ... to unearth the full truth of who put the live rounds on the Rust set."

"The questions of who introduced the live rounds onto the set and why are the central questions in the case."

4. Why wasn't the gun thoroughly inspected?

According to an affidavit filed Oct. 27, Halls told investigators that he didn't check all the rounds of the gun before handing it to Baldwin on the day of the shooting.

Typically, "I check the barrel for obstructions, most of the time there's no live fire, (Gutierrez-Reed) opens the hatch and spins the drum, and I say cold gun on set," Halls told authorities, the warrant says.

Halls was previously fired from another film production in 2019 after a firearm was "unexpectedly discharged" and a crew member suffered a minor injury, a producer of the Civil War-era drama "Freedom's Path" told USA TODAY in a statement.

In an interview with Fox News on Nov. 1, Halls' attorney Lisa Torraco raised doubts about who handed Baldwin the gun on set.

"This idea that my client grabbed the gun off of a prop cart and handed it to Mr. Baldwin absolutely did not happen," she said. But Torraco appeared to backpedal on this statement, refusing to give a direct answer when asked if Halls was the last person to touch the gun before handing it to Baldwin.

Maggie Goll, an IATSE Local 44 prop maker, also said in a statement that she filed an internal complaint with the executive producers of Hulu’s 2019 anthology series “Into the Dark” over concerns about Halls' behavior on the set. In an email to The Associated Press, Goll said Halls disregarded safety protocols for weapons and pyrotechnics and tried to continue filming after a crew member "slipped into a diabetic fugue state.”

Baldwin was asked during his ABC interview why he didn't check the gun himself and said he was taught years ago that "if I took a gun, and I popped a clip out of a gun or I manipulated the chamber of a gun, they would take the gun away and redo it. … We don’t want the actor to be the last line of defense against a catastrophic breach of safety with the gun.

“When that person who was charged with that gun handed me that weapon, I trusted them.”

5. What will happen to Alec Baldwin?

Santa Fe District Attorney Mary Carmack-Altwies said during a news conference in October she isn't ruling out charges being brought against Baldwin. "No one has been ruled out at this point," Carmack-Altwies said. But it's "probably weeks, if not months, of follow-up investigation that we’re going to need to get to the point of charging," she added.

Legal experts say it's unlikely the "30 Rock" actor will face criminal charges, unless evidence suggests the actor behaved irresponsibly with the gun, despite knowing the risks. In the investigation so far, there is no evidence to support that.

The actor said during his ABC interview that he doesn't expect to face charges: “I've been told by people who are in the know, in terms of even inside the state, that it's highly unlikely that I would be charged with anything criminally.”

He added: "Someone is ?responsible for what happened, and I can't say who that is, but I know it's not me."

Baldwin has publicly and privately offered his support to Hutchins' family in the weeks since her death. The cinematographer's husband, Matthew Hutchins, hired a wrongful death attorney. Meanwhile, Baldwin tweeted last month that every film and TV set should have police presence to help "monitor weapons safety," fake guns or otherwise.

Contributing: Kim Willis and Pam Avila

Could Alec Baldwin be charged? And who is liable in Halyna Hutchins' death? Legal experts weigh in

This article originally appeared on USA TODAY: Alec Baldwin 'Rust' shooting: Key questions linger about trigger, ammo