Complex sentence: The ritual of the sin offering began with the offerer (s) confessing their sins over the head of the victim; in the case of community offerings the elders performed this function; in the case of Yom Kippur, the high priest performs this task.
Split into simpler sentences: The ritual of the sin offering began with the offerer (s) confessing their sins over the head of the victim. In the case of community offerings the elders performed this function, in the case of Yom Kippur, the high priest performs this task.