WASHINGTON, DC - APRIL 27:  Paul Manafort, advisor to Republican presidential candidate Donald Trump's campaign, checks the teleprompters before Trump's speech at the Mayflower Hotel April 27, 2016 in Washington, DC. A real estate billionaire and reality television star, Trump beat his GOP challengers by double digits in Tuesday's presidential primaries in Pennsylvania, Maryland, Deleware, Rhode Island and Connecticut. "I consider myself the presumptive nominee, absolutely," Trump told supporters at the Trump Tower following yesterday's wins.  (Photo by Chip Somodevilla/Getty Images)
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WASHINGTON, DC - APRIL 27: Paul Manafort, advisor to Republican presidential candidate Donald Trump's campaign, checks the teleprompters before Trump's speech at the Mayflower Hotel April 27, 2016 in Washington, DC. A real estate billionaire and reality television star, Trump beat his GOP challengers by double digits in Tuesday's presidential primaries in Pennsylvania, Maryland, Deleware, Rhode Island and Connecticut. "I consider myself the presumptive nominee, absolutely," Trump told supporters at the Trump Tower following yesterday's wins. (Photo by Chip Somodevilla/Getty Images)
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(CNN) —  

Justice Department special counsel Robert Mueller is comparing notes with the office of New York Attorney General Eric Schneiderman on the Russia investigation, a source familiar with the investigation told CNN Thursday.

The two offices’ discussions include the New York attorney general’s investigation into former Donald Trump campaign chairman Paul Manafort, which started earlier this summer, the source said.

Politico, citing several people familiar with the matter, first reported on Wednesday that Mueller had teamed up with Schneiderman to investigate Manafort and his financial transactions.

It’s not unusual that both offices would be talking to one another about the probe, the source familiar told CNN, since they are working on the same investigation. The source added that some of the investigators working in Mueller’s office come from the Southern District of New York, adding to the closeness between the two offices.

A spokesman for the office of special counsel declined to comment.

Since the US president is unable to pardon state crimes, the collaboration could also be seen as an effort to pressure Manafort to cooperate in the broader Russia investigation under Mueller, Politico reported – however, the source told CNN that it premature to speculate about that at such an early stage in the investigation.

The move Politico reported on Wednesday night could be another indication that Mueller is ramping up pressure on Manafort. He has not been accused of any wrongdoing but is seen as a central figure in Mueller’s investigation into Russia’s 2016 election meddling.

Messages to a Schneiderman spokesperson weren’t returned.

CNN reported on Tuesday that Mueller issued subpoenas to Manafort’s former lawyer and his current spokesman, but it is unclear what specific information the Justice Department investigators believe they may have.

Additionally, earlier this summer, FBI agents raided Manafort’s home as part of the ongoing Russia investigation.

On Friday, Trump issued his first pardon to former Arizona Sheriff Joe Apraio, an early Trump supporter who had been convicted of criminal contempt related to his crackdown on illegal immigration.

CNN’s Evan Perez contributed to this report.