Interpol has been asked to contact Gardai about a Basque separatist who may be living in Dublin in a house belonging to one of the Colombia Three.
Madrid Judge Eloy Velasco wants to question Jose Ignacio de Juana Chaos, 52, in connection with a complaint accusing him of 'glorifying terrorism'.
The Spanish embassy said he applied for a passport giving his address as a house belonging to Jim Monaghan.
Mr Monaghan was one of three men accused of training Farc rebels.
The trio were sentenced in their absence after fleeing the South American country, to 17 years in jail for training Farc the Colombian rebel group.
Mr Chaos was sentenced to 3,000 years in prison for 25 murders in the 1980s, but was released early last month and travelled to the Irish capital.
It is understood the Spanish asked Interpol to help after he allegedly committed the offence of being a "terrorist apologist" by writing a letter read out at a public meeting expressing his support for ETA's campaign of violence