One of the men arrested in relation to the Ken Fetherstone murder investigation has been released without charge.
A file is being prepared for the Director of Public Prosecutions.
Two other men and a woman remain in garda custody.
The body of the 26-year-old father of one was found in the Dublin Mountains on 31 January.
Three men were arrested on suspicion of murder, while a woman is being held for withholding information.
Two of the men, aged 23 and 29, were arrested this morning in Dublin.
Two others were arrested yesterday afternoon; the 47-year-old woman was arrested in Gorey, Co Wexord, while a 48-year-old man was arrested in Rathfarnham.
Kenneth Fetherston was last seen alive on 22 September last year.
