Katherine Jackson Says Nephew Trent Jackson Set Up Hidden Cameras to Spy On Her

Katherine Jackson says her nephew is not just stealing money from her ... he's also secretly monitoring her every move around her own home with hidden cameras and microphones.

Katherine, 2 of her kids -- Jermaine and Rebbie -- and several friends and attorneys all filed declarations to support her elderly abuse claims against Trent Lamar Jackson. In docs, the 86-year-old matriarch says Lamar copied the key to her bedroom door, and she thinks he has the whole house wired for sound and video.

She says "the only place I can try and have a private conversation, is in my bathroom, pretending I am using the restroom so I can make a call." Katherine adds she tends to get dressed in her closet, out of fear Trent will walk in on her.

She claims Trent is listening from another line to her phone calls to see who she's talking to ... in order to isolate her from them. Katherine believes he's stealing by putting his name on her businesses and using her credit cards.

Perhaps worst of all, she claims Trent ignored her when she once thought she was having a stroke or a seizure, and, instead of calling 911 ... insisted he could take care of her.

Some of Katherine's children have beef with Trent too. Rebbie says in docs, Trent blocked her phone number on her mother's phone, and tried to have her removed from Katherine's medical directive.