Reuters:

Miller is the third associate of Stone to be identified as having been contacted by Mueller’s investigators. Jason Sullivan, a social media expert from California hired by Stone during the 2016 election campaign, recently flew to Washington to appear before Mueller’s grand jury.

John Kakanis, who worked for Stone as an assistant and driver, has also been subpoenaed to give testimony to Mueller, Reuters reported last month.

It feels like Mueller is just toying with Stone at this point.