Causeless murder in Gangnam station

There was a murder case at bathroom of singing room in Gangnam station may 17. The male suspect getting one sword was waiting woman entering in bathroom for a long time. Just as soon as female victim entered the bathroom. The male suspect commited a crime brutishly. and He was caught by police officer around one station a few hours after. The victim and suspect was an utter stranger. his murder motive is that he has neglected by other women. so commited a crime. later he was proved he had a men