A new report into the fatal shooting on the set of the movie Rust appears to cast doubt over star and producer Alec Baldwin's accounts of events.
Mr Baldwin denies pulling the trigger of the prop gun which went off, killing cinematographer Halyna Hutchins.
Weapons experts have now said the trigger would have "had to be pulled".
The actor's representatives told the PA news agency they had no comment to make on the latest development in the ongoing case.
Charges of involuntary manslaughter against Mr Baldwin were dropped in April, but prosecutors said it did not "absolve Mr Baldwin of criminal culpability".
They said charges against the star could be refiled over the October 2021 shooting, which occurred on the set of the western movie.
A new report, written by weapons experts Lucien Haag and Mike Haag, was given prosecutors in New Mexico on Tuesday.
According to the documents, prosecutors previously stated that they had information that there had been an alleged modification of the gun used by Baldwin on the Rust set.
Lawyers for Rust armourer Hannah Gutierrez Reed, who was also charged with involuntary manslaughter, said the Haags' report "does not indicate any modification to the gun" and "specifies that the trigger had to be pulled".
"Although Alec Baldwin repeatedly denies pulling the trigger, given the tests, findings and observations reported here, the trigger had to be pulled or depressed sufficiently to release the fully cocked or retracted hammer of the evidence revolver," said an excerpt of the weapons report included in the court documents.
"If the hammer had not been fully retracted to the rear, and were to slip from the handler's thumb without the trigger depressed, the half cock or quarter cock notches in the hammer should have prevented the firing pin from reaching any cartridge in the firing chamber."
It continued: "If these features were somehow bypassed, a conspicuously off-centre firing pin impression would result."
Last week, Ms Gutierrez-Reed pleaded not guilty to involuntary manslaughter and evidence tampering charges, related to the shooting.
Her plea came ahead of a jury trial scheduled for 6 December looking into the death of Ms Hutchins at the age of 42.
It is not yet clear whether or not the findings of the new report will result in charges against Mr Baldwin being refiled.
rules for thee.... just arrest this asshole already. He may not have known the gun was loaded, but he pointed it and pulled the trigger. That would get any Joe Shmoe a manslaughter charge.
I'm not sure it's that simple? I don't know the details of this specific case, but are you suggesting that every actor that ever uses a prop gun has to do a test fire? Doesn't the gun need to be reloaded after firing? How would the actor then know that it's safe after the reload? I don't think this is as easy as you make it seem. The process for such things needs to be tighter with strict controls and responsibilities. There are entire teams dedicated to the safe use of these props, and it's not just the actor's responsibility.