What is Islam's ruling on a liar who leads people in prayer?

Lying is a reprehensible trait and a characteristic of hypocrites. Its emanation from an Imam who leads people in prayer is even more ugly and egregious. It is obligatory to advise him, remind him, and urge him to repent. Lying necessitates transgression (fusuq), and praying behind a transgressor is disliked by jurists, even though the prayer is valid. If there is another Imam available, it is more appropriate to pray behind him than behind the transgressor. It is not permissible to appoint a transgressor as an Imam when it is possible to appoint a righteous person.