Li Zhibin, deputy director of the Public Security Department of Inner Mongolia autonomous region, committed suicide on Thursday morning, according to local police.

The police said Li, who was also vice-mayor and director of the Public Security Bureau in Hohhot, hanged himself to death in the lounge of the bureau. After investigation, the police ruled out the possibility of murder.

According to the suicide note found next to the body, Li was suffering from depression and was dependent on sleeping pills to fall asleep every day.

Li, 51, a native of Inner Mongolia, served in various posts in the public security departments for 31 years. He was named director of the Public Security Bureau in Hohhot in 2015 and then was promoted to be the deputy director of the Public Security Department of Inner Mongolia autonomous region in 2016.