The police worked hard and could only conclude that Gao Tong killed herself.
At that time, Gao Tong and Yi Hai's relationship was found out so she was perplexed. There was also the stress from school so there was a high possibility of her committing suicide.
However, Yi Hai didn't believe this and her family didn't, either.
They forced the police to investigate.
But no matter how they investigated the case, no one was suspicious at all.
Yi Hai was kidnapped by Ming Shu on that day so these three people who were the most suspect could be witnesses for each other.
Also, Ming Shu and Bei Tang had no motive to kill a student they didn't know.
Most importantly, the results from the forensic expert showed that she died from drowning. There were no signs of struggle on her body and it seemed as though she fell down herself.