Roger Stone, a former political adviser to US President Donald Trump, has been ordered to appear in court this week over Instagram posts that chastised and appeared to threaten the judge presiding over his criminal trial.
US District Judge Amy Berman Jackson said Stone would need to show cause at a hearing on Thursday as to why the posts did not violate a gag order in the case or the conditions of his release.
Stone, who is free on a $US250,000 ($A350,000) bond and is free to travel to certain US cities without the court's permission, has pleaded not guilty to charges of making false statements to congress, obstruction and witness tampering as part of Special Counsel Robert Mueller's investigation of Russian meddling in the 2016 election.
Stone's lawyers filed a formal apology with the court on Monday, after he posted a photograph on Instagram of Jackson alongside what appeared to be the crosshairs of a gun.
He later deleted the image and re-posted it without the crosshairs before removing it again, according to other media outlets.
Next to the close-up image of Jackson's face, Stone said Jackson was an "Obama appointed Judge who dismissed the Benghazi charges" against Hillary Clinton. He also accused Mueller of being a "Deep State hitman".
Stone later posted a statement on his account saying the photo was not intended to threaten the judge or disrespect the court.
He also said the image was not of cross hairs, but rather, the "logo of an organisation" often featured in many photos.
A representative from the US Marshals Service, the law enforcement arm of the federal justice system, did not immediately have a comment when reached on Tuesday.
Stone's posts about the judge came just days after Jackson issued a partial media gag order on Stone and his lawyers.
Friday's order prohibits them from speaking with the news media or making statements near the federal courthouse about the case.
It does not stop Stone from discussing the case when he is away from the courthouse, though it cautions that doing so may not be in his best interest.
Jackson also said in her order she may amend it in the future if necessary, an issue that she is likely to bring up in court later this week.
Australian Associated Press
