Paul Manafort has already been indicted on 23 counts by special counsel Robert Mueller’s team — but in a new filing Monday night, Mueller accused the former Trump campaign chair of yet more wrongdoing: attempted witness tampering.

Though Mueller hasn’t filed new charges yet, he moved to prevent Manafort’s release from house arrest on bail because, Mueller argued, the FBI had probable cause to believe Manafort has recently been attempting to tamper with potential witnesses.

Mueller claims that after Manafort was indicted on a second set of charges this February, he and a close associate “repeatedly contacted” two people they’d worked with in the past “in an effort to secure materially false testimony” in the case.

The special counsel says he’s obtained encrypted messaging, call records, and witness testimony to back him up — and that Manafort’s release should be blocked as a result.

Since his initial indictment last October Manafort has been held on house arrest and trying to meet his $10 million bail by putting up various properties. In recent weeks, it looked as if he was finally close to making it. But now, Mueller says that because there’s probable cause to believe he committed a crime here, his release should be blocked. You can read Mueller’s whole filing here.

How Mueller says Manafort tried to tamper with witnesses

The underlying matter at issue here is not Russian collusion or interference with the campaign — matters Manafort has not faced any charges over — but Manafort’s work for the pro-Russian Ukrainian government several years back.

Mueller has charged Manafort with 5 counts in Washington, DC, and 18 in Virginia related to this lobbying work. The charges include, among other things, conspiracy to defraud the United States, acting as an unregistered agent of a foreign principal, filing false income tax returns, bank fraud, and failure to report foreign financial accounts. Manafort has pleaded not guilty on all of them.

Mueller’s team claimed in their February indictment that, as part of the Ukraine lobbying, Manafort paid a group of former senior European politicians that he called the “Hapsburg group” to advocate for Ukraine’s interests in the United States.

Manafort seemed to believe his strongest defense would be to claim that he did pay these politicians to advocate for Ukraine’s interests — but only in the European Union, not the United States. And he wanted to make sure that two unnamed people from a PR firm with whom he’d worked on the project would stick to that story.

So, per Mueller, within days Manafort tried to reach out to one principal in that PR firm — someone referred to as “Person D1” in the indictment. Mueller alleges that:

On February 24, Manafort called Person D1, but he quickly ended the call.

That same day, Manafort used an encrypted messaging app to text the person “This is paul.”

On February 25 and 27, Manafort tried to call Person D1.

On February 26, Manafort sent Person D1 an encrypted message with a news article about the Hapsburg group allegations, and then wrote: “We should talk. I have made clear that they worked in Europe.”

But Person D1 talked to the FBI instead. He said that, contra Manafort’s claims, he knew the Habsburg group worked in the United States too. And, Mueller alleges, Person D1 thought Manafort was trying to suborn perjury.

Another set of surreptitious communications came from a longtime associate of Manafort’s whom the special counsel calls “Person A.” Mueller claims that, in February and April of this year, this Manafort associate repeatedly tried to contact the two PR firm principals, on behalf of someone he called “my friend P.” This person also tried to emphasize Manafort’s message that the Hapsburg group “never lobbied in the US.”

The second PR firm principal, “Person D2,” also told the FBI that he knew this wasn’t true, and that the Hapbsurg group did in fact lobby in the US.

And it’s not even the first time Mueller has accused Manafort of trying to improperly influence the trial — back in December, Mueller accused Manafort of secretly ghostwriting an op-ed piece by a Ukrainian politician about his work.