Canon 23
That a penitent shall not be admitted to the clergy.
If there is such necessity, a penitent may be classed among ostiarii or among lectors but will not read the Gospel or the Apostle. If, however, they are ordained, they shall remain among subdeacons, but will neither impose hands nor touch the sacred [things]. We call "a penitent" one who having commited a homicide or various other crimes and most serious sins after the baptism, did the public penance in the cilice, and was reconcilated to the divine altar.
(trans. M. Szada)