A woman (47) remains in custody today in connection with the murder of Kenneth Fetherston whose body was found in Dublin mountains last month.
The father-of-one had been missing for four months before his remains were discovered in a boggy ditch off Military Road in Rathfarnham in January.
Gardaí investigating the case yesterday arrested three men and a woman in Dublin and Wexford.
The three men were later released without charge.
Mr Fetherston may have been killed when he sought the return of money he had given to somebody known to him.
Gardaí, however, do not believe Mr Fetherston was involved in any criminal activity
He was last seen on September 22nd, 2009 at Landy's Industrial Estate on the Knocklyon Road in Dublin.
He had been driving a red Honda Civic, registration number 93 D 44862, which was found in a layby on the N11 near Gorey, Co Wexford four days later.
He left his apartment at the Tallaght Cross Hotel shortly before 9am that morning.