He testified to congress about his leak to his law school professor. This is in congressional testimony.
https://www.nbcnews.com/politics/justice-department/justice-department-won-t-prosecute-comey-over-leak-his-memos-n1038326
https://www.nbcnews.com/politics/justice-department/department-justice-declines-prosecute-comey-over-leaked-memos-n1047706
https://thehill.com/policy/national-security/459267-doj-watchdog-says-comey-violated-fbi-policies-in-new-report
This testimony was public, I watched it on TV!