The surveillance video shows Aleksander Tomaszewski, 33, who was charged with sexual abuse and stalking last month, walking to the back of the cell and hitting himself 40 times in the 4-minute video, reported the Eugene Register-Guard on Tuesday.
Tomaszewski later claimed in a signed statement that police had assaulted him while interrogating him.
After being told about the video, the inmate admitted to filing the false claims in hopes of getting released.
Tomaszewski ended up with two black eyes and additional charges of attempted coercion and initiating a false report. He was also fined $500 and sentenced to 20 days in jail.