An interesting video by Dr Barry Taff, regarding the infamous "Entity" case in Los Angeles. While I disagree with some of his interpretation of some of the photographic evidence, it is still an intriguing case. Of particular interest: Dr Taff talked about testing background radiation levels with Geiger counters. He reported that while the phenomena was peaking there was no reading. But when the phenomena stopped, the background radiation levels returned to normal.
https://youtu.be/irL6cZY0D2c
Bummer. The video has been removed from YouTube, but I did find this link to the video on another website: http://www.disclose.tv/action/viewvideo/111987/The_Entity_Files_95_of_my_4000_cases_are_not_ghosts/