The Muang Chon Buri station was alerted at 10am to the suspected suicide of Kiartisak Chancham, 44, at the Chon Buri Vocational School.
A doctor determined that Kiartisak had died about eight hours earlier, said police. No sign of fighting was found in the room apart from a fallen chair, which the employee is believed to have used to hang himself with a nylon rope before apparently kicking over the chair.
Wutthinan Pimmeethirawat, a science teacher, said he tried to open the lab in the morning but found the door locked from inside. When another janitor opened it with a spare key, they found Kiartisak hanging by the rope.
Wutthinan said Kiartisak has started work at the school just two months earlier. He was quiet and rarely talked, he added.