Surveillance on BIAP/Qp/OSS would not be illegal, as he is the subject of a legitimate criminal investigation.
The sauce for you being under investigation BIAP/Qp/OSS is your public actions in the form of spamming for years with malicious intent to obstruct a communication line, making threats of violence over interstate communications, and the vile images you have posted.
BIAP you admitted being OSS and constantly display the same arrogant attitude and childish antics that are easily identified.