This leaves him with constant and severe pain which he overcomes with the use of painkillers , of which he takes more and more as the pain remains .
Early in season 4 , Cho injures his back when he is hit by a car while chasing a suspect .
This leaves Cho with constant and severe pain which Cho overcomes with the use of painkillers , of which Cho takes more and more as the pain remains .
Early in season 4 , Cho injures his back when he is hit by a car while chasing a suspect .