Deputy Attorney General Rod Rosenstein named former FBI Director Robert Mueller as the special counsel to oversee the FBI’s investigation of Russia’s efforts to influence the 2016 election.

The key here is that Mueller will not serve as a "special prosecutor" because, as Rosenstein says, “My decision is not a finding that crimes have been committed or that any prosecution is warranted.”

The selection of Mueller, a former federal prosecutor who oversaw the FBI during the 9/11 attacks, was widely hailed by the political community as a great selection - Republicans and Democrats alike.

“Mueller is a great selection. Impeccable credentials. Should be widely accepted.”  - -  Rep. Jason Chaffetz, chairman of the House Oversight Committee.

“Excellent.”  - -  Sen. Dianne Feinstein, ranking Democrat on the Judiciary Committee

ROBERT MUELLER.   Mueller, 72, served as FBI director under Presidents George W. Bush and Barack Obama and was the longest serving head of the bureau since J. Edgar Hoover. In the aftermath of the Sept. 11 attacks, as the U.S. was ramping up security, he joined then-Deputy Attorney General Comey in threatening to resign if the White House overruled a Justice Department opinion that domestic wiretapping without a warrant was unconstitutional. 

Before joining the FBI, Mueller served as U.S. Attorney in San Francisco and held other positions in the Justice Department. Obama asked Mueller to stay in office 2 years beyond the normal 10-year term.