Bek was a Prylar of the Bajoran religion during the Occupation of Bajor. During the time of the Kendra Valley Massacre he was the liaison for the Vedek Assembly and the Cardassian Occupational Government. Two days after the massacre, Bek hung himself on the Promenade of Terok Nor and claimed in his suicide note that he gave the Cardassians the location of the resistance fighters in the Kendra Valley.
In actuality, the information was given by Kai Opaka and Bek hung himself to protect the truth of Kai Opaka's involvment. (DS9: The Collaborator)