A dead man was found floating in Khlong Rangsit canal in Pathum Thani’s Thanya Buri district on Wednesday.
The unidentified man, aged 30-35 years, was wearing brown boxer shorts, a cream shirt with red floral art and black socks.
The body was noticed floating in the canal near Khlong 12 public park in tambon Bueng Namrak about 7am by a passing motorist, said Pol Lt Col Amnart Nakvijit, investigation chief at Thana Buri police.
Police found only 20 baht in the man's pocket. He had tattoos on his arms and body and was wearing a watch. The left side of his head had a severe injury caused by a hard object. The man had been dead at least 48 hours before his body was found, Thai media reported.
A long-sleeve black jacket and a pair of white canvas shoes believed to belong to the dead man were found on the bank further along the canal.
Pol Col Wiwat Assawawiboon, chief of Thanya Buri police station, said residents told police they heard what sounded like two gunshots in the area around 10pm two days ago. However, they had not seen anybody.
Police would examine recordings of surveillance cameras in the area, he said.
His body was sent to Thammasat Chalerm Prakiat Hospital for a post-mortem examination, pending identification.