(CNN) The indictment and arrest of longtime Donald Trump associate Roger Stone Friday morning in Florida fills in a big missing piece of the emerging picture that special counsel Robert Mueller is painting: The Trump campaign actively sought to communicate and coordinate with WikiLeaks in regard to stolen emails aimed at damaging Hillary Clinton's campaign.

According to the indictment , which was unsealed on Friday, a "Senior Trump campaign official" was "directed to contact Stone about any additional releases and what other damaging information Organization 1 had regarding the Clinton Campaign. STONE thereafter told the Trump Campaign about potential future releases of damaging material by Organization 1."

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Organization 1 is WikiLeaks, the website run by Julian Assange that was responsible for the posting/distribution of emails stolen as a result of a hack of the Democratic National Committee's servers and the account of Clinton campaign chairman John Podesta. According to the US intelligence community, that hacking was conducted by the Russians for the express purpose of improving Trump's chances (and hurting Clinton's chances) in the 2016 election.

The first release of hacked emails came July 22, 2016 -- just before the opening of the Democratic National Convention in Philadelphia. Five days later, at a news conference, then-candidate Donald Trump said this: "Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing, I think you will probably be rewarded mightily by our press." (On that same day, according to filings from Mueller's office, the Russians began an effort to hack into Clinton's personal email server ; it's not clear whether that move was long planned or spurred by Trump's comments.)

When another tranche of hacked emails -- this time from Podesta -- were released on October 7, the "senior Trump campaign official" sent Stone a text message that read "well done." Stone, according to the indictment, bragged about his foreknowledge of the October 7 release and his correct prediction that it would be damaging for Clinton's campaign.

Which, wow.

Taken all together, what the revelations in the Stone indictment make clear is that, at a minimum, Stone was acting as a conduit -- or at least trying to act as a conduit -- between the Trump campaign and WikiLeaks. And was doing so at the behest of a "senior Trump campaign official."

There are two key things that we don't fully know:

1) The nature and extent of the conversations and communications between the senior Trump campaign official and Stone. The indictment is very vague about that. Here's the key pertinent bit:

"During the summer of 2016, Stone spoke to senior Trump Campaign officials about Organization 1 and information it might have had that would be damaging to the Clinton Campaign. Stone was contacted by senior Trump Campaign officials to inquire about future releases by Organization 1."

So, we know Stone was directed to seek out more information about what WikiLeaks had on Clinton by someone in the Trump campaign. But we don't know who knew and/or signed off on Stone's efforts. Or how closely the campaign was tracking Stone's attempts to secure more information on the leaks.

2) The nature and extent of Stone's contacts with WikiLeaks. The indictment makes clear that Stone lied to investigators about both his advance knowledge of planned WikiLeaks releases and his contact with the Trump campaign regarding his relationship with WikiLeaks. But it's not clear from the indictment whether Stone was coordinating the release of the hacked emails with WikiLeaks or simply had a very basic knowledge of the planned time frame for the release of the stolen emails and their contents. It's not clear whether Stone ever spoke directly with Assange, for example. And all of this is made even more complicated by the fact that Stone, long before the 2016 campaign, has a well-earned reputation as a braggart who often sought to exaggerate his own importance, influence and power within the political world. Was he simply puffing himself up to the Trump campaign in regard to what he knew about the WikiLeaks releases? Or did he actually have in-depth, advance knowledge?

Regardless, Stone is the 37th person or entity to be charged in the Mueller probe. He is the sixth Trump associate -- joining Michael Flynn, Rick Gates, Paul Manafort, George Papadopoulos and Michael Cohen -- to be charged in connection with the special counsel investigation into Russian interference in the 2016 campaign.

On Friday morning, White House press secretary Sarah Sanders told CNN that the Stone arrest "has nothing to do with the President."

Jay Sekulow, an attorney for Trump, told CNN in a statement: "The indictment today does not allege Russian collusion by Roger Stone or anyone else. Rather, the indictment focuses on alleged false statements Mr. Stone made to Congress."

But Stone is someone with a long history with Trump -- dating back to the 1970s when Trump mentor Roy Cohn introduced the two men. They stayed in touch throughout the intervening decades and occasionally worked on both business and political projects together. In 2012, Trump said this of Stone:

"Roger has a great understanding of the media. He understands politics and he understands politicians. And he always likes to take on somebody that at least has a good chance of winning. And sometimes it doesn't work out. He's had some people that I said, what are you doing with these people that, you know. But he loves it and he loves the game. He has fun with it and he's very good at it."

And when Trump announced for president, Stone was a senior adviser. He was fired two months later.

While Sanders' denial of any connection to Trump is predictable, her refusal to rule out the possibility that it was Trump who directed the "senior campaign official" to have Stone reach out to WikiLeaks is notable. She told CNN that she had yet to read the indictment, adding: "I'm not an attorney -- I'm not able to get into the weeds on this subject."

All of which leaves us where, exactly? With more answers -- Stone's role as an attempted conduit between WikiLeaks and the Trump campaign is now firmly established by Mueller -- but lots more questions about who knew what when, and how high up in the Trump campaign hierarchy that knowledge went.

Bottom line: The indictments and arrests just keep piling up. And with each new one, it becomes clearer and clearer just how many ties members of Trump's orbit had to the Russian effort to sway the election for their candidate.