It’s another dramatic development in Trumpworld: Paul Manafort, Trump’s former campaign chairman, is now cooperating with special counsel Robert Mueller in exchange for a reduced sentence for crimes involving bank fraud, money laundering and tampering with witnesses.

This might seem like another ominous turn for Trump, who must now contend with at least three former loyalists cooperating with federal prosecutors. But Manafort came and went quickly in Trump’s orbit, and he probably knows little to nothing about how Trump’s web of businesses operates. His value to Mueller could turn out to be minimal.

Mueller is investigating Russia’s role in the 2016 U.S. presidential election, along with any connections between the Trump campaign and Russian interests. But he ended up prosecuting Manafort for matters unrelated to the Trump campaign, as his mandate permits. Manafort earned millions doing consultant work for a Ukrainian strongman, without paying U.S. taxes on the money or registering as a foreign lobbyist. His Ukrainian clients were linked to Russian president Vladimir Putin. But there’s no evidence Manafort worked for Putin or any Russian interests directly.

Manafort joined the Trump campaign fairly late, in March of 2016, as campaign convention manager. In May, Trump promoted him to campaign chairman, in charge of the whole election effort. But Manafort’s Ukraine lobbying became controversial, and he left the Trump campaign on August 19, 2016. His total tenure with the campaign lasted five months.

[Check out the four homes Manafort must forfeit.]

Still, Manafort attended the now-notorious meeting at Trump Tower in June of 2016, when a Russian lawyer offered damaging information on Trump’s Democratic opponent, Hillary Clinton. If there’s more to the story involving Trump contacts with Russian operatives, Manafort may know. But there may not be more to the story. The meeting may have been just a clumsy (and possibly illegal) attempt to gain an edge against a formidable opponent by campaign bumblers. It’s Mueller’s job to get to the bottom of it.

Some analysts think the bigger risk to Trump involves business activities before he became a presidential candidate. Trump has sold property to Russian oligarchs and borrowed money from Russian lenders. He’s done business with Aras Agalarov, a Moscow construction tycoon close to Putin. In 2008, Trump’s son, Donald Jr., said the Trump Organization sees “a lot of money pouring in from Russia.”

There’s not necessarily anything wrong with that. But Russia is essentially a kleptocracy, and it’s possible Trump has handled hot money or made unsavory deals that might be embarrassing or illegal. It’s also possible Putin, a former KGB spymaster, deliberately tried to compromise Trump at some point—a longstanding Russian tactic—on the off chance he might become an important American official someday and subject to blackmail on matters of Russian national interest.