I know that the FBI took documents and blueprints and they released most of those files but they basically covered mostly everything in those documents with ink but why? And i have been reading too many conspiracy theories to know what’s true or not, and I’m not a expert in what the FBI does with documents so I might have got some information wrong but I hope you guys get the basic idea.
I am unaware of anything being taken or covered with ink. The FBI had the "Custodian of Enemy Property" seize and examine his belongings, since this was during WWII. Expert opinion was that there was nothing that needed to be kept from an enemy. Everything was eventually shipped to Belgrade.