Special Counsel Robert Mueller has issued two grand jury subpoenas for a social media consultant hired by Roger Stone, a longtime adviser to President Donald Trump, before the 2016 election, Reuters revealed Wednesday.

While Mueller’s office declined to comment, a lawyer for Jason Sullivan, the consultant, confirmed the subpoenas were delivered to his legal team last week. Sullivan heads the social media firm Cyphoon.com, and Stone supposedly hired him to help with strategy for a pro-Trump political action committee established by Stone.

The development gives some indication of the direction of Mueller’s probe into allegations that Russians attempted to influence the 2016 presidential election and that members of the Trump campaign may have known about or even been involved with those efforts.

The subpoenas, Reuters notes, “suggest that Mueller is focusing in part on Stone and whether he might have had advance knowledge of material allegedly hacked by Russian intelligence and sent to WikiLeaks founder Julian Assange, who published it.”