It was Uzi. Lemme explain. It's the start of the sentences each of the characters said. J started with "Understatement" , Uzi started with "Zoo" and V started with "I'm", now if you take the first letter of each of those words, it spells "Uzi", which means it was her. Another detail is her eyes, with the yellow pupils, Cyn controlled Uzi to kill N, you're welcome :P