Jeff Chiu, Associated Press
FILE - In this April 21, 2016 file photo, attorney and former FBI Director Robert Mueller, right, arrives for a court hearing at the Phillip Burton Federal Building in San Francisco.

Many questions have been raised concerning the influence Russia has had on the U.S. presidential election. While we would have preferred a congressional investigation, the appointment of former FBI Director Robert Mueller as a special counsel is a good start in helping the American people get the answers they deserve.

Special counsels — or prosecutors — come fraught with potential for mischief. In the past, they have expanded the original scope of their appointments, presumably because an investigation into one thing sometimes exposes another. They have faced political pressure to find evidence of wrongdoing, and their work sometimes has taken years.

Kenneth Starr, for instance, was appointed to look into the suicide of Vince Foster and the Clintons’ White Water investments, but he ended up looking into much more over the years, including the president’s extramarital dalliances.

We understand, however, that sometimes politics and conflicts of interest are such a powerful factor that nothing short of an independent counsel can determine the truth of a scandal. If the nation must have a special counsel, Robert Mueller, former long-time FBI director who won the support of both a Republican and a Democratic president, is an excellent choice.

A law governing the selection and monitoring of special prosecutors expired in 1999. Today, the rules are less clear. The president likely would have power to fire Mueller one day if he wished, but Mueller’s credibility makes such a move politically difficult.

Now that he is in place, Mueller should commit to doing a thorough job as quickly as possible. The American people deserve as much.

It is a sad commentary on the need for this investigation that deputy Attorney General Rod Rosenstein had to be the one to appoint Mueller. Attorney General Jeff Session was forced to recuse himself because he failed to tell the Senate about his own meetings with the Russian ambassador to the United States.

It appears Mueller’s probe will focus on former national security adviser Michael Flynn and former Trump campaign chairman Paul Manafort.

Flynn was fired for apparently lying to the vice president about talking, before the election, with the Russian ambassador about U.S. sanctions on Russia. He also is accused of accepting money from Russia for a trip without proper disclosure.

Manafort has extensive ties to Russians who are close to President Vladimir Putin.

It seems quite likely that the investigation will spread to include the president as well. Specifically, Americans need to know why Donald Trump did not fire Flynn until the media exposed his obfuscation, even though the acting attorney general at the time, Sally Flynn, had warned Trump about him.

In addition, Americans need to understand why Trump fired former FBI chief James Comey, whether it was an obstruction of justice to ask Comey to stop investigating Flynn’s ties to Russia and whether Trump tried to get Comey to promise not to investigate his own involvement.

And then there are questions about Russian involvement in the 2016 election, including the release of Hillary Clinton’s emails.

That is plenty to occupy the agenda of any special counsel. Mueller, who once stood up to President George W. Bush concerning the FBI’s involvement in torture, ought to have the skills and the courage to go after this quickly and thoroughly.

The good news is that the appointment of Mueller just may allow Congress to return to its normal daily activities without constant questions about potential administration wrongdoing.