>> reporter: he decided to interview the two american teachers who discovered carolyn's body, kathy patrick and sandra ames. under questioning, ames made a shocking accusation, that her roommate, kathy, murdered carolyn and staged the scene to look like a robbery. >> it never occurred to any of us that the killer was among us. >> reporter: who do you believe held the knife and murdered carolyn abel? >> kathy patrick. >> reporter: south korean officials issued this warrant for patrick's arrest, but she had moved back to washington state. investigators there quickly learned they were powerless to arrest patrick because the u.s. and south korea didn't have an extradition treaty. >> my sister never got to live her life. why does kathy get to live a full life? >> reporter: kathy turned down our request for anerew.s thbuil. so we went to her office at western washington university, where kathy patrick is a guidance counselor. there are investigators from two countries that have now-- are certain that you murdered carolyn abel. what do you have to say? >> uhm, i have to say that i'm innocent. >> r

kathy patrick and sandra ames. tion that her roommate, kathy, murdered carolyn and staged the scene to look like a robbery. >> it never occurred to any of us that the killer was among us. >> reporter: who do you believe held the knife and murdered carolyn abel? >> kathy patrick. >> reporter: south korean officials issued this warrant for patrick's arrest. but she had moved back to washington state. investigators there quickly learned they were powerfulless to arrest patrick -- powerless to arrest patrick because the u.s. and south korea didn't have an extradition treaty. >> my sister never got to live her life. why does kathy get to live a full life? >> reporter: kathy turned down our request for an interview. >> there is the building. >> reporter: we went to her office at western washington university where kathy patrick is a guidance counselor. there are investigators from two countries that have now -- are certain that you murdered carolyn abel. what do you have to say? >> i have to say that i'm innocent. >> repo