After Ibudan had been arrested for murdering a Cardassian officer, he was sent here. He often held with Bajoran dissidents. One of them taught Ibudan methods of tri-phasic cloning, which Ibudan used after his release in 2369 to create a clone of himself. He then attempted to frame Odo for his own murder by killing his clone.
When Major Kira kidnapped Surmak Ren to force him to develop an antidote to the aphasia virus the same year, he threatened she'd spend the rest of her life in Kran-Tobol prison if she didn't take him back immediately. (DS9: "Babel")