Cheng Zhi was a Chinese national and former government official that 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. After the death of ConsulKoo Yin during a CTU raid, Cheng relentlessly pursued Jack Bauer, who he thought responsible for it. He eventually captured him and tortured him for 2 years in China. Although he surrendered him back to the US at the beginning of Day 6, Cheng returned to steal a Russian FB subcircuit board. This caused an international incident that resulted in his incarceration. However, he managed to escape and attempted to cause a war between China and the US using a defense override module. Although Cheng's plot was thwarted by Jack Bauer, he still managed to order the murder of Audrey, which prompted Jack to behead him with a samurai sword.
Andre Drazen: I had a sister once. She was full of life like you. She was a photographer, took hundreds of pictures. I used to love looking at them. I can't do that anymore. You know how she died? Has anyone told you? Your father killed her.