The Rev. Joseph Lowery, one of the King family's closest friends and knew all of the King children since birth, told reporters he did not know the cause of her death Tuesday night. However, a spokesman for the King Center in Atlanta told The Atlanta Journal-Constitution that family members suspect she had heart problems.
Known as "Yokie" since childhood, King was born in 1955 in Montgomery, Ala., and went on to become an actress. She also was an author and continued her father's campaign for non-violence.
Her mother, Coretta Scott King died in January 2006 of complications from ovarian cancer following a stroke and mild heart attack.