FACTBOX: Who is George Mitchell?

(Reuters) - Former Senate Democratic leader George Mitchell, who has been probing the use of steroids in Major League Baseball, will issue his highly anticipated report Thursday, officials say.

Here are some facts about Mitchell.

* The owlish former Democratic senator from Maine was Senate majority leader from 1988 to 1994.

* He was named in March 2006 to lead an investigation of steroids in baseball, including accusations against slugger Barry Bonds as he approached the all-time home-run record.

* Mitchell received the Presidential Medal of Freedom on March 17, 1999 -- St. Patrick's Day -- for his role in bringing together Protestant and Catholic leaders in Northern Ireland to sign the 1998 Good Friday Accord aimed at stemming the long-standing bloody conflict there.

* He served as chairman of the board of the Disney Co. while the entertainment giant was wracked by shareholder dissent after a no-confidence vote in chief executive Michael Eisner.

* Mitchell led a five-member commission appointed by President Bill Clinton to find ways to halt Israeli-Palestinian violence, and remained a voice calling for the United States to take an active role as Middle East mediator during the George W. Bush administration.

* A lawyer, judge and fast-rising senator, Mitchell was also considered as a possible Supreme Court justice and secretary of state.

* Born in Waterville, Maine, on August 20, 1933, Mitchell was the fourth son of a janitor of Irish descent and his Lebanese immigrant wife.

* Mitchell earned his undergraduate degree from Bowdoin College in 1954, and served in Berlin as an officer in the U.S. Army Counter-Intelligence Corps until 1956. He received his law degree from Georgetown University Law Center in 1960.

* He worked as a trial lawyer in the Justice Department, and then served as executive assistant to Democratic Sen. Edmund Muskie of Maine from 1962 to 1965.

* After practicing in a private Maine law firm until 1977, Mitchell was appointed U.S. attorney for Maine. He later became U.S. district judge for the state.

* In 1980, Mitchell was appointed to fill out the Senate term of Muskie, who resigned to become secretary of state. Mitchell was elected to the seat in 1982 in a come-from-behind run and again in 1988 with a whopping 81 percent of the vote.

* Mitchell shocked his Senate colleagues when he announced he would retire at the end of 1994. Once considered a possible new baseball commissioner, he instead joined a Washington law firm and married for the second time.

(Writing by Vicki Allen and Paul Grant, editing by Todd Eastham)