WASHINGTON – A federal judge raised the prospect Tuesday of sending Roger Stone to jail after his Instagram account featured a picture of the judge Monday.

U.S. District Judge Amy Berman Jackson ordered Stone to appear Thursday to explain why his pretrial release shouldn’t be modified or revoked. She also raised the prospect of imposing a more restrictive gag order.

Stone, a flamboyant political consultant and off-and-on adviser to President Donald Trump, had been released on personal recognizance after he was arrested at his Florida home last month. He was charged by special counsel Robert Mueller’s team has charged Stone with obstruction and lying to Congress for statements about his contacts with Wikileaks, which released damaging emails about Democrat Hillary Clinton before the 2016 election.

Stone has pleaded not guilty and said any misstatements were mistaken recollections rather than intentional lying. He has protested his innocence and attacked prosecutors on social media and in a series of television interviews.

Stone's Instagram account featured a picture on Monday of Jackson’s face against a background with what appeared to be a gun’s crosshairs. The accompanying text featured a plea for contributions to Stone's defense fund and noted the judge was appointed by former President Barack Obama.

The picture was removed later that day. Stone said the post had been a random picture taken from the internet and wasn't meant to threaten or disrespect the judge.

“Please inform the court that the photograph and comment today was improper and should not have been posted,” Stone wrote in a note filed with the court Monday. “I had no intention of disrespecting the court and humbly apologize to the court for the transgression.”

The U.S. Marshals Service, which protects federal judges, was aware of Stone's post, spokesman Drew Wade said on Tuesday. He declined to comment on whether the service had provided additional security to Jackson.

Contributing: Kevin Johnson