GARDA investigating the murder of Ciaran Noonan have arrested a man in his 30s.
The suspect, who was picked up in north Dublin yesterday, is the fourth person to be arrested as part of the investigation.
Sources told the Herald today that it is the "most significant" arrest so far.
However, he is being held on suspicion of withholding information, rather than for being involved in Mr Noonan's abduction and murder.
The Coolock man is being detained at Store Street Garda Station. Gardai are working on the theory that murdered Dublin dad Ciaran Noonan was set up by a young woman who knew him.
Noonan (29), whose decomposed body was found dumped in a ditch last Friday night, was abducted as he walked with his cousin on Russell Avenue in East Wall on the evening of October 20.
Detectives say the abduction was ordered by a Coolock drugs gang to whom Noonan owed a five-figure drugs debt.
It has now emerged that a former girlfriend of a gang member had seen him with his cousin in the East Wall a couple of hours before he was abducted.
A local source said: "This woman knew the gang were after Ciaran -- they had been looking for cash off him for months. She is suspected of phoning a gang member and tipping them off that Ciaran was in the East Wall area -- there is a lot of anger about this."
The woman, who is in early 20s and is suspected of being a cannabis dealer, was arrested by gardai two weeks ago but was later released without charge. A file is now being prepared for the DPP.
She is one of four people to have been arrested by detectives investigating the murder.