Two of Martin Luther King Jr.'s children have filed a lawsuit against a third, embroiling the family in a legal dispute over the estate of the civil rights icon.

Bernice King and Martin Luther King III filed a lawsuit Thursday in county court to force Dexter King to open the books of their father's estate.

The lawsuit claims that Dexter King, the estate's administrator, is refusing to provide his two siblings with documents concerning the estate's operations. That includes financial records, contracts and other documents, the lawsuit said.

Jock Smith, an attorney who plans to represent the elder siblings in the case, said Friday that the decision to sue their brother was not an easy one.