He had left a death note in which he has confessed about his participation in the murder and asks for forgiveness.
Four men had been found stabbed to death in an apartment in Rezekne on Jan. 3. According to the initial version, there had been an argument during a drinking bout, after which four men were killed.
On Sunday two men aged 31-34 were detained, both of them having previous criminal record.
The police has launched a criminal procedure on an aggravated murder, and the crime carries a life sentence.