A Nakhon Sawan man died of suffocation after a charcoal fire was lit inside his rented room in Samut Prakan's Phra Pradaeng district on Wednesday, police said.
The manager of the boarding house on Soi Suksawat 78 in Tambon Bang Chak called police at 10.30pm after the mother of Nopparat Supakijejjakorn, 24, could not contact him by phone.
She called the management of the boarding house. When officials and police opened the room they found Nopparat lying dead on the bed.
A doctor determined that he died about eight hours before he was found.
Police found two empty beer bottles and a suicide note.
All the ventilation sources had been sealed with plastic sheets.
Consumed charcoal was found in an aluminium bowl in the middle of the room.
The body was sent to the Police Hospital.