Margaret O’Neill was last seen in Swords at 8am on Tuesday.
The man is due to appear before the Criminal Courts of Justice morning.
Gardaí searched a house in Tallaght on Thursday.
He is expected to appear before a sitting of Tallaght District Court later this morning.
Kian Dwyer was last seen in Sligo town and is believed to have travelled to Tallaght in Dublin.
Eileen Agnew is described as being 5’4″, of slim build with blond hair.
Thieves made off with a “large amount of copper piping and wire” from the Fortunestown store.