https://www.dailykos.com/stories/2017/9/8/1697113/-Mueller-reportedly-seeking-to-interview-Trump-s-inner-circle-family-members-included
"Each of the six advisers was privy to important internal discussions that have drawn the interest of Mueller’s investigators, including his decision in May to fire FBI Director James B. Comey and the White House’s initial inaction following warnings that then-national security adviser Michael Flynn had withheld information from the public about his private discussions in December with Russia’s ambassador to the United States, according to people familiar with the probe."