Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) The Justice Department is preventing Senate investigators from interviewing two top FBI officials who could provide first-hand testimony over the firing of former FBI Director James Comey, the latest sign that Special Counsel Robert Mueller could be investigating the circumstances around the firing, officials tell CNN. The previously undisclosed turf war comes as the Senate judiciary committee has not yet given assurances to the special counsel's office that it could have unfettered access to the transcript of the interview it conducted last week with the President's eldest son, Donald Trump Jr., saying that the full Senate must first authorize the release of the information to Mueller's team.The Senate judiciary committee wants to interview FBI officials as part of their probeThe congressional investigations investigating Russian interference are clashing with DOJ 
 Question:"Both the judiciary committee and the special counsel are engaged in important investigations, and we are committed to being as cooperative with Mueller's office as we can, which is why we've been in ongoing communication with _'s team," Hartmann said.

Robert Mueller