The mutilated body of a 29-year-old man, who posted a goodbye message on Facebook, was found on the tracks near the Ban Khok Phet railway station in Tambon Muang Khong in Khong district early on Friday.
Khong police were alerted to the death of Suthat Wanglomklang, 29, at 12.24am.
The body was taken to Khong district hospital.
The man did not carry an identification card but his identity was confirmed when his family contacted the hospital to claim the body.
The family told police Suthat had a mental disorder and had attempted to commit suicide once before. He left home at 9pm and his Facebook showed his post, saying "goodbye" at 10.10pm.