The questions about what happened between Jan. 26 and Flynn's firing on Feb. 13 appear to relate to possible obstruction of justice by President Donald Trump, say two people familiar with Mueller's investigation into Russia's election meddling and potential collusion with the Trump campaign.
Multiple sources say that during interviews, Mueller's investigators have asked witnesses, including White House Counsel Don McGahn and others who have worked in the West Wing, to go through each day that Flynn remained as national security adviser and describe in detail what they knew was happening inside the White House as it related to Flynn.