The sheriff investigating the shooting incident involving Alec Baldwin on the set of the movie "Rust" said the investigation is now focused on the presence of live ammunition on the set.

Santa Fe County Sheriff Adan Mendoza appeared Thursday on the "Today" show, where he discussed the ongoing investigation and noted that the main point that authorities are looking into is how live ammunition made its way to a set that allegedly didn’t require its use. 

"I think during the interviews, the focus of the investigation is how the live rounds got there, who brought them there and why they were there," Mendoza explained. "As far as if it’s going to rise to the point of negligence or the point of criminal charges, we’re hoping to work with the district attorney in reference to that so it’s a clear determination if charges should be filed."

Mendoza said during a press conference Wednesday that, despite armorer Hannah Gutierrez Reed saying there was no live ammunition kept on set, a live round was recovered in director Joel Souza’s shoulder — that same bullet passed through cinematographer Halyna Hutchins, resulting in her death. 

In addition to the bullet removed from Souza’s shoulder, investigators found 500 rounds of ammunition, including a mix of blanks, dummy rounds and what appeared to be live rounds.

ALEC BALDWIN ‘RUST’ SHOOTING: SHERIFF SAYS 'THIS IS STILL A CRIMINAL INVESTIGATION': LIVE UPDATES

Baldwin has since spoken out about the incident, calling it a 'tragic accident' and praising Hutchins as a "deeply admired colleague." (Jim Weber/Santa Fe New Mexican)

The sheriff noted that he does not believe that live ammunition had any necessity to be on the set and is therefore looking into how and why it was there at all. 

"The information that we've got in the industry is that there should be no live rounds on set," he explained. "So, again, we’re going to try to determine why they were there and who brought them there." 

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One hypothesis as to the presence of live rounds being on set has to do with rumors that the crew used the guns in their off time for leisure to do target practice. According to TheWrap, unnamed crew members reported others using the gun that same day in the morning to go "plinking," an activity in which people shoot at beer cans with live ammunition for fun. Mendoza said he has not been able to confirm those reports yet.

District attorney Mary Carmack-Altwies speaks at a news conference on Oct. 27.  (REUTERS/Adria Malcolm)

"I’m aware of the statements, there have been statements that were made that there was a live-fire and target practice on the set," Mendoza said. "We're going to track down that information and try and confirm whether that’s a fact or not."

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He concluded his interview by calling on anyone with knowledge of the alleged live-ammo target practice to come forward to investigators.

An aerial view of the film set on Bonanza Creek Ranch where Hollywood actor Alec Baldwin fatally shot cinematographer Halyna Hutchins (VIA REUTERS)

"Again, our investigators are aware of those statements and we encourage anybody that has information that took place and when that took place to come forward with that information."

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In addition to Baldwin and Gutierrez Reed, the investigation is also focused on assistant director Dave Halls, who said in a search warrant obtained by Fox News Wednesday that he did not check all of the rounds inside the gun to ensure that they were "dummy" rounds. However, given that no live rounds were supposed to be on set at all, it’s still unclear how one entered the revolver at all.