Cheng Zhi was a Chinese national and former government official who turned to terrorist activities after feeling betrayed by his country. During Day 4, Cheng served as Head of Security at the Chinese consulate in Los Angeles. When Consul Koo Yin was killed during a raid on the consulate, Cheng was appointed by Deputy Consul Su Ming to lead the investigation. Cheng eventually learned from one of the agents involved that Jack Bauer was behind the attack on the consulate and captured him at the end of Day 5.