The presidential tweets came as Manafort’s trial was entering its second day in U.S. District Court in Alexandria, Virginia.

Serafini said that while Trump “probably did mean” his tweets “as favorable to Manafort,” there was a risk of Trump’s Twitter followers viewing Manafort in a negative light because of the juxtaposition with Capone, who ended up going to prison on tax-related charges, not for his bloodier crimes in Prohibition-era Chicago.

Gerald Lefcourt, a criminal defense lawyer in New York, said Trump’s “tweets sound like a message is being sent to Manafort to stay strong and if things go bad I have your back.”

Lefcourt said Trump appeared to be hinting at the possibility of a pardon for Manafort.

Neither prosecutors nor defense lawyers at that trial mentioned Trump’s tweets to Judge T.S. Ellis III on Wednesday.

However, public comments in the past have led attorneys in a trial to request a mistrial.

In 1970, President Richard Nixon said that Charles Manson, who was then on trial for a series of killings carried out allegedly at his behest, “was guilty, directly or indirectly, of eight murders without reason.”

Manson’s lawyers then asked for a mistrial — which was denied.

Facing a backlash over his remarks, Nixon issued a statement saying “the last thing I would do is prejudice the legal rights of any person in any circumstances.”

“The defendants should be presumed to be innocent at this stage of their trial,” Nixon said.

Serafini, the former prosecutor, said he did not believe that Trump’s tweets were grounds for a mistrial in Manafort’s case. He said he has tried cases before Ellis in the past, and the judge could instruct jurors to not pay attention to anything they see about Manafort on Twitter or elsewhere.

Dan Mangan reported from Englewood Cliffs, N.J., and Kevin Breuninger reported from Alexandria, Va.