The lawsuit for return of the papers was filed Wednesday against Howard Nelson Ballou in U.S. District Court in Jackson. It says Ballou's mother worked for King from 1955 to 1960 and kept documents from when King led the Montgomery Improvement Association and the Southern Christian Leadership Conference.
Attorneys for the estate say in court papers that the various letters, photograph and other items are worth more than $75,000.
Ballou works as news anchor for Jackson television WLBT. He has not responded to the lawsuit and did not immediately answer a request for comment.