18 U.S.C. § 1924 – Unauthorized removal and retention of classified documents or material — provides, in part:
(c) In this section, the term “classified information of the United States”means information originated, owned, or possessed by ...
Those who participated in destruction of evidence do as well.
The remaining question is if those investigators, prosecutors or their superiors at DOJ/FBI were involved in a conspiracy to obstruct the investigation/prosecution.