A Sofia prison guard was ordered a home arrest and two others went to bail over a recent prisoners sex scandal.
The three were accused of allowing a homosexual orgy last summer, with some of the participants now saying they had been abused.
Footage made with a mobile phone by an inmate recently emerged on the Internet, sparkling the scandal.
Made by then prisoner Yanko Vatashki, the recording seemed to show a repellent celebration of his birthday.
It showed several inmates in humiliating sexual action, and one of the involved men later said he was forced into the orgy.
An investigation should reveal why warders did not interfere, and whether participants in the shocking action were actually forced into it.
It also remains unclear how had Vatashki managed to keep his own mobile phone during the imprisonment.