The estate of the Rev. Martin Luther King Jr. claims a Mississippi man has in his possession a collection of rare documents once belonging to King — and they want them back.

A lawsuit, filed last week in U.S. District Court in Jackson, Mississippi, says Howard Nelson Ballou, a news anchor in Jackson, has the documents taken from the slain civil rights leader. Ballou’s mother was a former secretary of King from 1955 to 1960 and kept documents during the time King led the Montgomery Improvement Association and the Southern Christian Leadership Conference, writes the Associated Press.

After working for the Kings, Ballou’s parents went to work at what is presently Elizabeth City State University in North Carolina. Ballou’s father stored the documents in the university’s basement. No one knew they were there until university staff uncovered them in 2007 and returned them to the Ballou family. In 2010, the King family was alerted to the unearthed documents after a newspaper wrote about them.

Court records show the documents include a sermon, a statement King made the day after the landmark Supreme Court ruling on segregation, and a handwritten letter to Ballou’s mother from Rosa Parks. The material could also include photographs, the report adds.

"These documents and items are not only rare and irreplaceable, but of great value and historical importance as well," the lawsuit says. Attorneys for the estate estimate the items are worth more than $75,000, though the exact value is unknown.

Ballou’s lawyer, Robert Gibbs, says that the Ballous were close friends with both King and King’s wife, Coretta Scott King, and that whatever documents were given to Mrs. Ballou by the Kings are rightfully hers.