Detective Investigation Files - Season 2 Episode 36

The real identity of SUN, who works as the school janitor in the education centre, is confirmed. He admits that he is the one who killed YUEN and NAM to avenge CHI's death. All are under his control and the plan is made up by him. It seems that the case has been solved but YUNG suspects that it is not the end as the mysterious man who attacked CHING is still unknown. Later YUNG finds that the one who attacked CHING is SUM, another tutor. However he is shot to die. As SUN has been arrested, there is another killer. YUNG suspects that the killer is CHING's boyfriend CHRIS as he knows much about the education centre. However who is CHRIS?