In the 5 page PDF that's been shared throughout this thread and several sites for spikes Arrest, Detective Dave Foro writes that's they interviewed spikes about Buzzy's stolen clothes and that they later learned the entire animatronic was stolen. The detective states spikes denied any firsthand knowledge but gave some first names, no last names or any specifics.
All of that is mentioned in the orlando rising article with excerpts from the police document that kicked off this thread.
I don't know who reported it stolen.
But it was reported stolen and this detective put that in his report.
An arrest warrant for a separate alleged theft from Haunted Mansion mentions the Buzzy animatronic being reported stolen in November 2018.
orlando-rising.com