The lead prosecutor tasked with overseeing former FBI Director James Comey’s prosecution stemming from his post of seashells that the Justice Department claims amounted to a threat against President Donald Trump has withdrawn from the case, according to a court filing.

Matthew Petracca was the lone prosecutor from the U.S. Attorney’s Office for the Eastern District of North Carolina assigned to the case when it was unsealed late last month.

On Friday evening, however, the Justice Department filed a notice with the court indicating that Petracca has been replaced by assistant U.S. Attorney Timothy Severo.

The department did not include any explanation for the move in the high-profile case.

Comey’s attorneys are expected to make a vigorous push to have the case dismissed before it can go to trial through a variety of legal challenges.

A Justice Department spokesperson did not immediately respond to a request for comment from ABC News.

Comey was charged with threatening to kill Trump by posting a photo on Instagram of seashells on a beach arranged in the numbers “86 47.” Citing the slang meaning of “86” as to “nix” or “get rid” of something, allies of the president allege that the post was a veiled threat against Trump, who is the 47th president.

Following backlash over the post, Comey removed the photo from Instagram and said he was unaware that the post could be associated with violence.

Critics of Trump say the indictment is another effort by the administration to punish the president’s perceived enemies after a judge last year threw out an indictment against Comey on unrelated charges.

At a press conference announcing the charges last month, acting Attorney General Todd Blanche argued that Comey’s post crossed the line between First Amendment-protected speech and speech that warrants prosecution. 

Comey’s trial is scheduled to begin Oct. 21.