The corruption is compounding the fears of citizens who already put up with ordinary thugs, Archbishop John Njenga, chairman of the Catholic Commission for Justice and Peace, told the CISA news agency.
Torture is common during police interrogations to extort confessions, he said.
Peter Kimanthi, senior assistant commissioner of police for public relations, denied the allegations. He challenged preachers to address their flock, which he includes criminals.
Kimanthi said police training involves human rights, law, public relations, ethics and measures to combat fraud and cyber-crime.
But Bishop Philip Anyolo, who oversees the Uniformed and Disciplined Services Chaplaincy in Kenya, said that after graduating from the police college, the law officers seem to forget everything they were taught.
The bishop added, however, that the public itself can combat police corruption by refusing to offer gifts for services which are rightly theirs, and by observing the law and refusing to bribe.