A former U.S. intelligence contractor has sued fired FBI Director James Comey and other current and ex-government officials, alleging the bureau has covered up evidence provided to agents showing widespread illegal spying on Americans.

The suit, filed late Monday night by Dennis Montgomery, was assigned to the same federal judge who has already ruled that some of the National Security Agency’s collection of data on Americans violates the U.S. Constitution’s Fourth Amendment, setting up an intriguing legal proceeding in the nation’s capital this summer.

Documents obtained by Circa outside of the lawsuit show that the U.S. attorney’s office in Washington in 2015 approved a grant of limited immunity for Montgomery so he could explain how he managed to walk out of his contract work for several U.S. intelligence agencies with 47 hard drives of highly classified documents — a security breach potentially larger than Edward Snowden’s leak.

The documents show FBI agents interviewed Montgomery on videotape for several hours and collected the 47 hard drives.