US prosecutors on Monday accused Donald Trump's former campaign chairman Paul Manafort, who is facing multiple charges of money laundering, bank fraud and illegal lobbying, of attempting to tamper with witnesses.
A motion submitted by Special Counsel Robert Mueller, who is heading up the main investigation into alleged Russian election meddling, said that Manafort had contacted witnesses by phone and encrypted text messaging for the purpose of securing "materially false testimony."
It added that such activities amounted to a violation of his bail terms, which "triggers the statutory presumption in favor of detention," meaning he could face jail time ahead of his trials.
Manafort has been under home confinement since he was indicted in October.
According to the court document, he had sought to suborn perjury from witnesses who would be called to testify regarding the activities of the so-called "Hapsburg group" which allegedly carried out unlawful lobbying for Ukraine.
In February, the 69-year-old pleaded not guilty to charges of money laundering, illegal lobbying and lying, setting up the first trial to result from Mueller's investigation, due to begin on September 17.
Then in March he pleaded not guilty to charges of bank and tax fraud, setting up a separate trial for July 10.
Mueller's investigation has now entered its second year, and continues to dominate US politics while menacing Trump's presidency.
So far the investigation has issued 22 indictments -- of which 16 were for Russian individuals and companies associated with online meddling in the 2016 election.
The remaining include Michael Flynn, Trump's erstwhile national security advisor, who admitted guilt to one count of lying to investigators on December 1; Manafort's longtime partner and deputy campaign chair Rick Gates and campaign foreign policy advisor George Papadopoulos.
All three worked out plea deals and have pledged to cooperate with the investigation.
Earlier Monday, Trump downplayed Manafort's role in his election campaign and complained the FBI should have informed him that his chairman was under investigation.
"As only one of two people left who could become President, why wouldn't the FBI or Department of 'Justice' have told me that they were secretly investigating Paul Manafort," he asked.
"Paul Manafort came into the campaign very late and was with us for a short period of time (he represented Ronald Reagan, Bob Dole & many others over the years), but we should have been told that Comey and the boys were doing a number on him, and he wouldn’t have been hired!"