The family of the late US civil rights activist met thousands of mourners who came to the Rainbow PUSH Headquarters in Chicago to pay their respects.
Colvin was arrested for refusing to give up her bus seat to a white person months before the famous case of Rosa Parks.
The records shed light on the investigation of the black teenager's death, which galvanised the US civil rights movement.
In August 1964, three civil rights activists were found dead in the Deep South. The public's response provided the impetus for new civil rights legislation in America.
About 230,000 pages of records are unsealed, despite opposition from some of the King family.
The civil rights activist visited the town just days before his assassination in 1965.
The Six Triple Eight tells the story of the only black, all-women US battalion in World War Two.
The revolutionary campaigner spoke at the Oxford Union on 3 December 1964 - 60 years ago.
The family of the murdered black civil rights activist accuses the agencies of having a role in his death.
