Pol Maj-General Charoen Srisasalak said the action was in line with the Criminal Code.

Meanwhile, Pol Colonel Dr Pornchai Sutheerakune, head of the Institute of Forensic Medicine at Police General Hospital, said the autopsy report showed that Wanchai’s death was caused by a gunshot to the head, damaging his brain, which was self-inflicted.

Wanchai, 60, took his life at a small Bangkok hotel on Thursday evening after hours of negotiations with police and relatives who had urged him to surrender. The stand-off was covered by an army of media personnel, with many TV channels broadcasting the incident live.

Acting city police chief Pol Lt-General Sanit Mahathaworn, meanwhile, said everyone had done their best in the case. He urged society to learn lessons from this saga.

‘He said he wanted nothing’

Sanit said police got a hint of Wanchai’s whereabouts, when he fled after killing his colleagues. He had emailed a relative’s daughter about conflicts he had led to the killings. Arriving at the hotel on Suttisan Winitchai Soi 1, police found Wanchai exhausted and under stress in a parking lot with a pistol pointing to his temple.

Sanit said police didn’t want to use violence as he had no hostage and it might lead to more loss of life, so they negotiated with him. Police also got people the man trusted to try to convince him to put the gun down. “While we were talking, we asked him what he wanted and he said he wanted nothing.”

“He apologised for causing trouble to others. He said he was afraid of going to jail and being executed. He kept saying he wanted to leave this body. He appeared to relax; he then looked at the watch and suddenly shot himself. We did the best we could. I still feel sorry for not being able to save him and I want this to be a lesson for everyone.”

Wanchai was accused of killing two holders of doctorate-degrees – Pichai Chaisongkram, 56, and Nattapon Chumwor-athayee, 54 – by shooting them in the back of their heads while they were giving an oral exam to a master’s student on campus. Later, during the intense talks, Wanchai threw two suicide notes towards police during negotiations. They included violent language on how he felt about the two victims.

What Pichai had done to him was “a deliberate offence to his dignity. A person can be killed, but his dignity cannot be challenged”, he stated. In another letter about Nattapon, Wanchai laid out nine points mostly about his disgruntled feelings over the Master’s degree student examinations and that he had planned to kill Nattapon for two years but changed his mind.