While popular media has often portrayed Jim Garrison, the New Orleans District Attorney behind the infamous Clay Shaw trial, as having been targeted by the federal government for retribution, a look at his FBI file reveals the exact opposite - according to the documents, Garrison’s investigation was considered so toxic and aggressive that Director J. Edgar Hoover ordered no agents have any contact with him. When third parties began providing the FBI with evidence that Garrison had engaged in fraud against the government, the Bureau cautioned against investigating him, precisely because of how Garrison would inevitably frame it.
As early as February 1967, the FBI Director had ordered the Bureau’s agents to avoid all contact with Garrison and his investigators. Just days before a KGB planted story would appear in the Italian newspaper Paese Sera and redirect Garrison’s investigation to obsess over CIA connections, Hoover identified Garrison as “a person not to be contacted without prior Bureau approval.” This was the explicit result of Garrison’s already inflammatory investigation and accusations.
https://www.muckrock.com/news/archives/2017/aug/02/jim-garrison-fbi-jfk/