Spoilers for the latest episodes of Psycho-Pass.
During the riots, Kagari and Choe enter Sybil's core. There, Joshu Kasei forces a dominator into lethal mode to kill Choe. Then, she kind of melts down before killing Kagari as well.
Why was she melting down (her chin kind of falls down)? At first I'd have guessed it was because she was forcing the dominator, but later we see she can change their behavior with ease.