You didn't understand who the killer is, like me? I found the following answer on http://asianwiki.com/Fashion_King:
The killer is formed by Madam Ho and Jung Man Ho, action in killing is secretary Kim.
Planner and Plot is formed by Madam Ho and Jung Man Ho, Jae Hyuk only dare to make Young Gul bankrupt.
Secretary Kim told Ga Young as long as Young Gul contact you, do let us know immediately...
Jae Hyuk brought Ga Young back to New York to let her continue her study is to re-start a relationship at the same time to appear in front of Young Gul to prove that he is victory in winning Ga Young's love...
Jae Hyuk and Madam Ho knew where was Young Gul's new york house address...
Jae Hyuk is timid in killing, Madam Ho and Jung Man Ho formed the killing plot plan and action done by secretary Kim...
The killer is formed by Madam Ho and Jung Man Ho, action in killing is secretary Kim.
Planner and Plot is formed by Madam Ho and Jung Man Ho, Jae Hyuk only dare to make Young Gul bankrupt.
Secretary Kim told Ga Young as long as Young Gul contact you, do let us know immediately...
Jae Hyuk brought Ga Young back to New York to let her continue her study is to re-start a relationship at the same time to appear in front of Young Gul to prove that he is victory in winning Ga Young's love...
Jae Hyuk and Madam Ho knew where was Young Gul's new york house address...
Jae Hyuk is timid in killing, Madam Ho and Jung Man Ho formed the killing plot plan and action done by secretary Kim...