Deputy speaker of parliament Bolot Sherniyazov said deputy Tynychbek Akmatbaev was killed as part of a dispute between criminal groups.
Sherniyazov said Akmatbaev's brother is a member of a known criminal group and at the Moldavanovka prison, about 25 kilometers outside Bishkek, was a member of a rival criminal group.
Prime Minister Feliks Kulov also ruled out political motives for Akmatbaev's killing.
Kulov said Akmatbaev and his bodyguards violated regulations by bringing guns with them into the prison when they made their inspection.
Prison officials demanded the visitors surrender their weapons, they did so and prisoners stole the guns from prison guards.
Kulov also said the poor conditions in the prison sparked the riot.
Parliament voted to quickly allocate an additional $2.5 million from the state budget to improve conditions at the country's prisons.
(RFE/RL's Kyrgyz Service/Kabar/ITAR-TASS)