A 60-year-old murder could decide whether Robert Mueller can publish any findings obtained through a Washington grand jury.

Attorney and author Stuart McKeever has been investigating the disappearance of Columbia University professor and political activist Jesus Galindez for decades. While no body was ever found, Galindez — whose unsolved case is the subject of the 2003 movie The Galindez File — is believed to have been kidnapped while in New York City, flown to the Dominican Republic, and possibly killed there.

McKeever has requested the release of secret testimony given to a Washington, DC grand jury, but the Justice Department has resisted. They maintain that no judge has “inherent authority” to release information outside of those that fall under Congressional exemptions. Those exemptions do not apply to McKeever’s case — or Mueller’s.

“I’ve been on the journey almost 40 years to tell this story,” McKeever told Politico on Sunday. “The Justice Department does not want this case to break the dam.” McKeever says the “sleeper case” could have massive ramifications:

If the D.C. Circuit were to accept the Department of Justice’s arguments…that would have potentially enormous implications for the future of the information from the Mueller investigation. That could close out a path by which that information becomes public.

The question will be largely moot if Democrats retake the House in November, because the information could simply be subpoenaed. But if the oft-speculated “blue wave” does not reach the tide markers, a decision on McKeever’s request could set a far-reaching precedent in Washington.

Three judges will decide the issue: Trump appointee Judge Greg Katsas, Obama appointee Judge Sri Srinivasan, and Reagan appointee Judge Douglas Ginsburg. Of course, there is potential for the panel to avoid directly affecting Mueller’s investigation. They could specify that their decision is only meant to apply to McKeever’s specific request or send it back to a district court.

The case is Stuart McKeever v. Jeff Sessions, No. 17-5149 in the U.S. Court of Appeals for the District of Columbia Circuit.