Here are 10 facts, just the facts, about Robert Mueller.

1. Robert Swan Mueller III’s nickname at Justice Department headquarters was “Bobby Three Sticks,” supposedly a reference both to the Roman numerals at the end of his name and the three-finger Boy Scout salute.

2. Mueller is at least the 31st person to be specially appointed to investigate federal wrongdoing. The first was John Henderson in 1875, hired and fired by President Ulysses Grant. In the intervening century before Watergate, just seven men looked into five cases. In the last 40 years, however, 24 people — 22 men and two women — have been told to ferret out the truth.

3. Mueller is the great-grandson of William Truesdale, who served from 1899-1925 as head of the Delaware, Lackawanna and Western Railroad, serving Pennsylvania, New York and New Jersey. Truesdale was credited with improving the DL&W, but he was less famous than the railroad’s fictional advertising character, Phoebe Snow, who promoted the company’s boast that its coal caused less soot. (The singer later known as Phoebe Snow was born Phoebe Ann Laub, and took her stage name from the railroad’s ad character.)

4. When Mueller was on the hockey team at St. Paul’s prep school in New Hampshire, one of his teammates was future Secretary of State John Kerry.

5. Mueller served 12 years as director of the FBI, the longest tenure since J. Edgar Hoover, but his law enforcement career was marked by a number of high-profile cases long before he rose to the top, including the investigation of mobster John Gotti, Panamanian strongman Manuel Noriega and the 1988 Pan Am Flight 103 bombing over Lockerbie, Scotland. According to Lisa Monaco, a former chief of staff, the Lockerbie case affected him particularly. For years later, Mueller quietly attended the December memorial services organized by the families.

6. When George W. Bush took office in 2001, Mueller became acting deputy attorney general and instantly established his work ethic. His own deputy, David Margolis, showed up to work the morning after the inauguration to find a note on his chair: “It’s 0700. Where are you?” The note was unsigned, but Margolis knew it was from Mueller. Margolis has another story about Mueller’s adherence to schedule: When Mueller was at Justice under George H.W. Bush, he hosted a barbecue for his aides from 8 to 11 p.m. “At five minutes to 11, he’d start flipping the lights to get people out of his house,” Margolis said.

7. His wife sometimes beats him at golf.

8. Mueller said he was inspired to serve in Vietnam because of the combat death of Princeton classmate and friend David Hackett. Mueller enlisted with the Marine Corps and graduated from the Army’s demanding Ranger school before ending up leading a rifle platoon in Vietnam in 1968. When his men came under heavy attack at Mutter’s Ridge, he kept his cool, supervised the evacuation of casualties and led a team into enemy territory to rescue a wounded Marine. He was awarded a Bronze Star with a V distinction for combat valor.

9. When Mueller was between government jobs in 2014-15, the NFL hired him to investigate the league’s handling of the Ray Rice case. Rice, a running back for the Baltimore Ravens, had been suspended for two games after a casino video showed him dragging his fiancee (now wife) from an elevator. But later a video leaked showing Rice punching his fiancee in the elevator, and the NFL suspended him indefinitely. Mueller investigated whether the NFL had seen the punching video before it leaked. He found no evidence that it had.

10. Mueller is often described in serious terms, but he isn’t without a sense of humor. In 2013, at a farewell event to celebrate his public service — at which one person joked he would “depart Justice for the last time, hopefully” — the remarks at times were reminiscent of a roast, and Mueller not only laughed along but took part. During his 8½-minute speech, Mueller told a story about a particularly tense senior staff meeting, where he admitted he was a “wee bit ill-tempered.” Mueller’s chief of staff, Lee Rawls, out of the blue asked, “What is the difference between the director of the FBI and a 4-year-old child?” The room grew hushed, and Rawls delivered the ice-breaker: “Height.”

Mark Jacob is the Tribune’s associate managing editor for metropolitan news. Stephan Benzkofer, a former weekend editor of the Tribune, is a freelance writer and editor.

mjacob@chicagotribune.com

Twitter @MarkJacob16

Sources: “Encyclopedia of North American Railroads,” edited by William D. Middleton, Rick Morgan and Roberta L. Diehl; “Coal Trains: The History of Railroading and Coal in the United States,” by Brian Solomon and Patrick Yough; “The Threat Matrix: Inside Robert Mueller’s FBI and the War on Global Terror,” by Garrett M. Graff; Donald C. Smaltz address at Gonzaga University; The New York Times; The Saturday Evening Post; Time magazine; The Washington Post; USA Today; CNN.com; Washingtonian.com; slate.com; c-span.org.