A weapons supervisor already facing involuntary manslaughter charges in connection with the 2021 shooting death of cinematographer Halyna Hutchins on the New Mexico set of the Western film "Rust" now faces an additional felony count.

In a court filing obtained by CBS News Thursday, special prosecutors Kari Morrissey and Jason Lewis charged the weapons supervisor, Hannah Gutierrez-Reed, with one count of fourth-degree tampering with evidence.

On the day of Hutchins' shooting, according to the court documents, Gutierrez-Reed is accused of transferring narcotics "to another person with the intent to prevent the apprehension, prosecutions or conviction of herself."

No details on the charge were provided.

In a statement provided to CBS News, Jason Bowles, an attorney for Gutierrez-Reed, criticized the new allegations, saying that "it is shocking that after 20 months of investigation, the special prosecutor now throws in a completely new charge against Ms. Gutierrez Reed, with no prior notice or any witness statements, lab reports, or evidence to support it."

On Oct. 21, 2021, on a film set outside Santa Fe, 42-year-old Hutchins was struck and killed when a prop gun being held by actor Alec Baldwin discharged during a rehearsal. Joel Souza, the film's director, was also wounded.

Following a lengthy investigation, both Baldwin and Gutierrez-Reed were charged with involuntary manslaughter in January.

In April, however, Lewis and Morrissey announced that the charges against Baldwin were being dropped because "new facts were revealed that demand further investigation and forensic analysis." They noted though that their "decision does not absolve Mr. Baldwin of criminal culpability and charges may be refiled." 

However, they said at the time the charges against Gutierrez-Reed would remain in place.

In court filings earlier this month in response to a request from Gutierrez-Reed's attorneys to have the involuntary manslaughter charges dropped, the special prosecutors said that they had witnesses who could testify that Gutierrez-Reed was "drinking heavily and smoking marijuana" at nights during the "Rust" production. They also claimed she was likely "hungover when she inserted a live bullet" into Baldwin's gun.

In March, as part of a deal with Santa Fe County prosecutors, "Rust" assistant director David Halls pleaded guilty to unsafe handling of a firearm and was sentenced to six months' probation.

On the afternoon of the shooting, prosecutors alleged in a probable cause statement filed in January, Gutierrez-Reed retrieved the gun from the prop truck and handed it to Halls without conducting a necessary safety check.

Prosecutors said Halls also did not request the safety check —which would involve Gutierrez-Reed showing Halls each dummy round in the gun— before he subsequently handed the weapon to Baldwin.

Filming on "Rust" resumed in April at Yellowstone Film Ranch in Montana. In late May, Baldwin said that he had wrapped filming on the production.

— Alex Sundby contributed to this report. 

In:
• Alec Baldwin
• New Mexico
• Shooting Death
• Halyna Hutchins