FACTBOX: Facts about Martin Luther King Jr

(Reuters) - Civil rights leader Martin Luther King Jr. was shot in Memphis 40 years ago today in a racially charged assassination.

Following are some facts about King:

* Born in 1929 in Atlanta, King gained national prominence in 1955 when he led the boycott of the bus system of Montgomery, Alabama, after Rosa Parks, a black woman, was arrested for refusing to give up her seat to a white man.

* King, a Baptist minister, emerged as a black leader as he led protests and marches across the country to end racial segregation in the South and establish equal rights. Protesters adhered to nonviolent tactics, despite often-brutal treatment by police and white citizens.

* King was arrested more than 30 times, his house was firebombed and he was harassed by the FBI. He won the Nobel Peace Prize in 1964. His "I have a dream" speech at a 1963 rally in Washington is regarded as one of the most stirring speeches of the 20th century.

* King was shot on April 4, 1968 at the Lorraine Motel in Memphis, where he was helping with a janitors' strike. His assassination set off race riots in more than 100 U.S. cities.

* Escaped convict James Earl Ray confessed to the crime and was sentenced to 99 years in prison, though he later recanted and sought a retrial. He died in prison in 1998. King's family and some others have said they believe Ray did not act alone. Several government investigations have failed to uncover credible evidence of a conspiracy.

* King's birthday, January 15, is celebrated as a national holiday.

SOURCES: The King Center; U.S. Justice Department; Nobel Foundation; Martin Luther King, Jr. Research and Education Institute; American Rhetoric

(Reporting by Andy Sullivan, editing by Vicki Allen)