A Bajoran held in Odo's cells for drunkenness in the episode Duet, who later stabs the Cardassian clerk Aamin Marritza to death on the Promenade simply for being Cardassian.
Kainon is a Bajoran civilian seen in the first-season Deep Space Nine episode Duet. He is first met in a holding cell in the security office, sleeping off a drinking bout, and loudly objects to being locked up beside a Cardassian prisoner.
That prisoner is Aamin Marritza, a filing clerk who has posed as the war criminal Gul Darhe'el in the hope of forcing Cardassia to face its guilt. Once Kira Nerys has uncovered the truth and resolved to let him go, she walks him along the Promenade.
Kainon steps out of the crowd and drives a knife into Marritza's back. When Kira protests that the man was no butcher, Kainon answers that being Cardassian is reason enough, a reply that Kira, changed by the affair, can no longer accept.