Serik Sarsenov said he believes that former security officer Rustam Ibragimov was not involved in the February assassination of Sarsenbaev and two of his aides.
Sarsenov said another two defendants in the trial -- including a former official in the Senate, Erzhan Utembaev -- should also be acquitted.
State prosecutors say Utembaev and Ibragimov plotted and carried out the triple murder and have asked the court to sentence them to death. They have also called for the other eight defendants in the trial be sentenced to between seven and 20 years in jail.
Sarsenbaev's relatives believe higher-placed officials are involved in the murder and have decided to boycott the final phase of the trial, calling it a "farce."
(Kazakhstan Today, Interfax-Kazakhstan)