During the Occupation of Bajor, he was a farmer until the Cardassians took Petra's mother. Even though he asked around, he never found out what happened to her, but assumed that the Cardassians raped her to death. After her disappearance, he ran away with Petra and joined the Bajoran Resistance. Two days later he killed his first Cardassian.
In 2370, he led the hijacking of the Phoenix. By this time he had become mentally unstable. When Jadzia Dax attempted to regain control of the tanker using subterfuge, Rizo discovered who she really was. He managed to stun her, but soon the tables were turned when he was knocked unconcious by Odo. When he came to, he babbled on about ghosts on ship. He was later confined to a cargo bay on the tanker.
Shortly after being confined, Petra was discovered to have hidden aboard the ship. After Dax and Odo found them together, Dax told Petra she could stay with her father in the cargo bay. Later, when the tanker was attacked by Cardassian fighters, Dax asked Rizo for his help in stopping them. He assisted, but soon turned on Dax. However, she managed to reason with him and he surrendered.
After returning to DS9 Rizo was taken in to custody by the Bajorans on charges of murder, piracy, and hijacking a Federation starship. Petra was sent to a mental hospital for evaluation. Meanwhile Rizo proposed to the government that he be allowed to help convert a prison facility into a factory to provide convicts a way to work for a free Bajor. The council went along with his recommendations, and sentenced him to life imprisonment. (DS9 novel: Antimatter)