Washington (CNN) President Donald Trump has hired well-known DC-based attorney John Dowd as part of his legal team, a source familiar with the hiring tells CNN.

Dowd previously led the investigation into former Cincinnati Reds player and manager Pete Rose over gambling charges for Major League Baseball and authored the report that led to the banning of Rose from the MLB.

Dowd additionally represented Republican Sen. John McCain of Arizona during the Keating Five Senate ethics investigation in 1990. McCain was one of five senators accused of corruption, but he was cleared of having acted improperly.

Trump is being investigated by Justice Department special counsel Robert Mueller for potential obstruction of justice when he fired former FBI Director James Comey, The Washington Post reported Wednesday evening.

Mueller is interviewing three top intelligence officials as early as this week as part of the probe, the Post reported, citing "five people briefed on the requests." It is the most significant sign yet that Mueller's investigation is extending beyond questions of Russian interference in the 2016 election.

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