The Russia investigation struck its first blows against Donald Trump’s presidency in a one-two punch Monday: his former campaign manager was arrested on numerous charges, and a lower-level adviser has admitted to communicating with intermediaries of the Putin government about stolen emails, has pleaded guilty to lying about it, and is now co-operating with authorities.

The day began with ex-campaign manager Paul Manafort surrendering to authorities as he and another senior campaign aide were slapped with a dozen criminal charges, including conspiracy against the United States; money-laundering; failing to register as a foreign agent; and lying to police.

The president seized on the fact that most of the alleged crimes occurred before he announced his presidential run in 2015: “Sorry, but this is years ago, before Paul Manafort was part of the Trump campaign,” he tweeted. ”Why aren’t Crooked Hillary (Clinton) & the (Democrats) the focus?????”

A moment later, the next shoe dropped.

A subsequent announcement from special investigator Robert Mueller’s office was about events that indeed occurred during the campaign, that did pertain to contacts with Russia, and specifically involved conversations about high-ranking officials and illicitly obtained Hillary Clinton emails.

The office announced that a foreign-policy campaign adviser to Trump was arrested three months ago, confessed this month as part of a plea deal, and is now co-operating with federal authorities as part of the expanding probe.

“Special counsel Mueller appears to have a co-operating witness,” tweeted former New York prosecutor Preet Bharara, recently fired by Trump.

“That is significant. Time will tell how significant.”

That witness is George Papadopoulos.

He has pleaded guilty to lying to police about events from the spring of 2016. They involved communications with a Russian professor with high-ranking ties to the Putin government, and with a woman he described in an email as “(Vladimir) Putin’s niece.”

Papadopoulos held meetings in Europe and repeatedly communicated with these people. Some of the communications involved setting up a Trump visit to Moscow in the hope of improving U.S.-Russia relations.

But some involved more shadowy political co-operation.

Papadopoulos said the professor offered to deliver dirt collected by Russians on Clinton in the form of emails — several months before sites like Wikileaks began mass-releasing emails that upended the American election.

According to the settlement sheet released Monday, Papadopoulos said: “(The Russians) have dirt on her,” and “the Russians had emails of Clinton,” and ”they have thousands of emails.”

It is unclear from the settlement document what emails he was referring to — whether they might be unreleased messages from Clinton’s time at the State Department, other personal emails, or the ones ultimately released months later by Wikileaks, belonging to the Democratic party and to Clinton campaign chair John Podesta.

The 14-page statement concludes with a cryptic line that portends potential storms ahead: “Following his arrest (on July 27, 2017), defendant Papadopoulos met with the government on numerous occasions to provide information and answer questions.”

Legal observers believe he might now try to flip Trump’s former campaign chair. Manafort and fellow senior campaign aide Richard Gates were hauled in by the FBI early Monday after being charged with 12 crimes.

Those two have pleaded not guilty.

Manafort is accused of allegedly laundering $18 million into the U.S., from work on behalf of the pro-Russia faction in Ukrainian politics, and of using more than three dozen shell companies to avoid paying taxes on this money, based in Cyprus and elsewhere.

He allegedly used the proceeds to fund a lavish lifestyle that included purchases of more than $1 million in antique rugs, and more than $1 million in clothing at stores in New York and Beverly Hills.

Manafort also worked as an unregistered lobbyist for a foreign power through 2014, authorities allege. It is illegal to work in the U.S. as a lobbyist for foreign interests without filing disclosure forms.

Furthermore, he and his co-defendant conspired in November 2016 and February 2017 to lie to federal investigators, according to the indictment sheet.

The 31-page indictment sheet appears to suggest one way federal investigators can exert pressure on Manafort to talk. It concludes by stating that if Manafort is convicted on these charges, he could be forced to forfeit his assets — which include four houses, and one life-insurance policy.

Manafort was released on bail, and placed under house arrest, for $10 million.

The White House played down the developments as a non-event.

A spokeswoman for Trump noted that the allegations against Manafort date back years. As for the low-level aide, she said Papadopoulos’ legal troubles don’t involve political collusion with Russia, but stem from his lying to police.

Spokeswoman Sarah Sanders said: ”It has to do with his failure to tell the truth. That doesn’t have anything to do with the campaign or the campaign’s activities.” She called Papadopoulos a low-level volunteer acting on his own.

In recent days, Trump and his supporters have launched a pre-emptive strike on the special prosecutor. They have aggressively pushed for prosecutors to shift the focus of the Russia investigation onto Hillary Clinton, and cast aspersions on Mueller.

That was reflected in the tone of coverage from friendly news outlets. Fox News covered Monday’s developments less extensively than other cable outlets, and took a shot at Robert Mueller in a segment Monday titled: “Credibility In Question.”

Democrats warned the president to leave the prosecutor alone.

”The president must not, under any circumstances, in any way, interfere,” said Democratic Senate leader Chuck Schumer. ”If he does, Congress must respond swiftly, unequivocally, and in a bipartisan way to ensure that the investigation continues and the truth, the whole truth, comes out.”

Alexander Panetta, The Canadian Press

Note to readers: This is a corrected story. An earlier version incorrectly said Manafort and Gates had pleaded guilty.