An 82-year-old researcher who has spent decades searching for an answer to the disappearance of a critic of former Dominican Republic dictator Rafael Trujillo is asking the U.S. Supreme Court to rule that district courts have inherent authority to release grand jury materials, a decision that could spill over into Congress’ quest to obtain grand jury evidence from the special counsel.

Stuart McKeever has been seeking a limited release of grand jury materials from the more than 60-year-old criminal prosecution of a former FBI agent believed to have been involved in the vanishing of Columbia University professor Jesus de Galindez from New York City in 1956.