The Klong Luang police reported the death of Akinare Prancesco Polize (not the official spelling), 22.
When police arrived at the apartment, his roommate, Jirawat Mapradit, 23, was still asleep.
Police checked and did not find any trace of fighting in the room. Officers took Jirawat for questioning.
Jirawat reportedly told police they had lived together for a month.
He said Akinare did not go to work on Tuesday and when he returned to the room at 8pm, the man appeared sad but he did not tell him anything.
Jirawat said he went into sleep at 2am on Wednesday and was woken up by the police.
Akinare apparently said he wanted to go to Italy to meet his father but he had financial problems.