The most ominous element of Robert Mueller’s latest court filing is the part that is illegible: the 60-odd lines that have been redacted in dark ink.
Among these paragraphs are details of an ongoing criminal investigation for which Michael Flynn, Donald Trump’s one-time national security adviser, has supplied “substantial assistance”, according to a sentencing memorandum submitted to the court by Mr Mueller, the special counsel.
That tantalising clue is one of many in the sentencing memo that suggests Mr Mueller’s probe into Russian meddling in the US election is poised to deliver even more scalps in the days to come. In addition to Mr Flynn, a former three-star general, Mr Mueller has already secured guilty pleas from — among others — Michael Cohen, Mr Trump’s former lawyer, and Paul Manafort, the president’s former campaign chief.
Mr Flynn has been a generous witness, according to the document, sitting for 19 interviews with the special counsel or other prosecutors over the past year. He was also well placed, serving in the Trump campaign’s inner circle before being appointed the president’s national security adviser.
In a worrying sign for the president and his closest associates, prosecutors tend to use co-operating witnesses — be they mafia figures, crooked executives or campaign officials — to reach higher up the organisational ladder.
“It’s very likely that we’ll see more indictments and that those indictments are going to involve recognised names,” said Mark Zauderer, a partner at Ganfer, Shore, Leeds & Zauderer. “It could mean an official in the campaign or it could mean a [Trump] family member,” he speculated.
A former prosecutor agreed, observing: “There are a limited number of people Flynn could be co-operating against who are above him . . . He was very senior.”
Mr Trump has previously dismissed the special counsel’s probe as a “witch-hunt” and an investigation in “search of a crime”. On Wednesday, with the president attending the funeral of George HW Bush, his Twitter account was uncharacteristically quiet.
Mr Mueller appeared to make a breakthrough in the probe last week after 18 months of closely guarded investigation. The plea he extracted from Mr Cohen marked the first time the prosecutor established a direct connection between Mr Trump’s business interests and Russia while the 2016 election campaign was under way — something the president has long denied.
Specifically, Mr Cohen claimed that he had briefed Mr Trump and his family members on their longstanding plan to build a Trump Tower in Moscow months after he had previously told Congress the project had been dropped. If so, say lawyers, that could create at least the possibility of a financial motive for Mr Trump to collude with Russia.
With Mr Flynn, an early and enthusiastic Trump supporter — leading chants against Hillary Clinton of “Lock her up!” at campaign rallies — the special counsel appears to have bolstered the link between the Trump inner circle and Russia.
Mr Flynn pleaded guilty a year ago to lying about his meetings with Russia’s US ambassador, Sergei Kislyak, in late 2016, before president-elect Trump had taken office.
During that time, Moscow was seeking a backchannel with the incoming team to reverse economic sanctions imposed by the Obama administration for its meddling in the US election and its aggression in Ukraine.
Whereas Mr Mueller and his team have had to ramp up the pressure on other Trump associates to co-operate, Mr Flynn appears to have flipped swiftly. His 19 meetings are unusual, say former prosecutors, and an indication of the wealth of material he was able to supply. Another indication of his value is that Mr Mueller gave him glowing reviews to the court while accusing others, including Mr Manafort, of lying.
“His early co-operation was particularly valuable because he was one of the few people with long-term and first-hand insight regarding events and issues under investigation by [the special counsel],” Mr Mueller wrote in a submission that recommends sparing Mr Flynn a prison sentence.
In particular, he noted, Mr Flynn has helped prosecutors with the collusion investigation, supplying them with “first-hand information” about interactions between the Trump transition team and Russian officials.
“This means that Flynn was able to tell Mueller about things that happened when he was in the room,” said Elie Honig, a former prosecutor who is now a white-collar lawyer at Lowenstein Sandler, noting the value of such testimony.
More intriguing to Mr Honig and others, though, is the former general’s assistance with a separate and ongoing “criminal investigation” mentioned in the memo. That investigation — conveyed in three redacted paragraphs — is listed in the court filing before the Russia probe, hinting at its importance — as does the heavy redaction. Just what it involves is a matter of speculation.
Mr Mueller’s Russia probe has already spawned several, separate investigations by state and federal prosecutors of those with ties to Mr Trump.
There may be further clarity in a matter of days. By Friday, Mr Mueller is to file a sentencing memo regarding Mr Manafort, which is expected to detail the instances in which prosecutors believe he lied to them, in violation of his plea agreement. Then Mr Cohen is to be sentenced next week.
In the meantime, though, Mr Flynn’s co-operation has provided much fodder for those observing the special counsel.
“There are plenty of clues you can pull out of that memo that show you that Mueller got a lot from Flynn,” Mr Honig said, “and that there is plenty to go.”