Special counsel Robert Mueller’s investigation into Russian interference in the 2016 election is scrutinizing a number of wire transfers involving millions of dollars sent by Donald Trump’s former campaign manger Paul Manafort, according to a report on Sunday.

The transactions, in which off-shore companies linked to Manafort moved $3 million around the globe between 2012 and 2013, are being examined to determine whether he was hiding money from tax authorities or whether he was helping his clients in the Ukraine launder money, BuzzFeed News reported.

Manafort took over running Trump’s campaign in May 2016 but was forced out just three months later when news reports began questioning his work for Ukranian President Viktor Yanukovych, who has close ties to Russian President Vladimir Putin.

A federal grand jury has approved an indictment in Mueller’s investigation and it could be released as soon as Monday, CNN reported on Friday. It’s unknown who’s targeted because the indictment is sealed.

But Manafort has reportedly been one of the main focuses of Mueller’s probe.

Armed federal agents carried out a pre-dawn raid of Manafort’s Alexandria, Va., home, seizing documents and materials a day after Manafort voluntarily testified to members of the Senate Intelligence Committee, which is investigating Russian meddling in the election.

And he has teamed up with New York Attorney General Eric Schneiderman to look into allegations of money laundering by Manafort.

The new investigation revolves around 13 wire transfers between 2012 and 2013 that were first flagged by American financial institutions, which are required by law to alert the Treasury Department to “suspicious activity,” the report said.

The transfers were made by five off-shore companies linked to Manafort and did not explain what the funds were being used for.

They also originated in places known for money laundering, including Cyprus and St. Vincent and the Grenadines in the Caribbean.

Much of the money ended up in the US through home improvement contractors, a hedge fund and a car dealership.

A Manafort spokesperson would not comment to BuzzFeed about the story.