In Rambam Hilchos Avodas Kochavim Perek 2 halacha 8 it says that if someone curses the name of God, the court examines the witnesses as to what they heard. The "great one" (Rambam's words) of all the witnesses repeats exactly what he heard without using fake names, and the rest say we heard the same.
My question is who what the "great one" means. Who decides which witness has to repeat what he heard? I would think nobody would want to volunteer to say such a thing, but rather say I heard what the first one said.