Kainon was a Bajoran citizen alive during the late-24th century. By his later life, he had developed a history of committing minor criminal offenses.
In 2369, Kainon was living on Deep Space 9 when he was detained for public drunkenness and placed into a holding area with the Cardassian Aamin Marritza. Kainon became quite vocal in his displeasure at having to share his cell block with a Cardassian.
After Marritza was released, Kainon, in his disdain for Cardassians, fatally stabbed Marritza declaring, "He's a Cardassian. That's reason enough!" Constable Odo then escorted Kainon back to his cell. (DS9: "Duet")
Appendices
Background information
Kainon was played by actor Tony Rizzoli in his only Star Trek appearance.
The script for "Duet" states the pronunciation of Kainon's name as "KAY-non" and goes on to describe him as, "an unkempt, even disheveled-appearing, mid-30's Bajoran" and a "thief/drunkard". [1]