GARDAI investigating the murder of Real IRA faction leader Alan Ryan have arrested a well-known criminal for questioning.
The suspect was detained by armed officers in Artane on the northside of Dublin. The man, who is aged 24, is from Coolock.
He was being held for questioning last night at Coolock garda station under section 50 of the anti-gangland legislation, the Criminal Justice Act 2007.
This is the fourth arrest in the investigation.
Ryan (pictured) was shot dead as part of an ongoing feud between his faction and a group of criminal gangs.
Gardai believe his murder was ordered by two gangland figures who had been put under pressure by Ryan and his associates to hand over a slice of the profits they were making from drug trafficking and extortion and protection rackets at pubs and clubs around the capital.
The reformed group, which now includes several former Provisional IRA activists, is part of the dissident alliance which was formed last summer.
Ryan (32) was gunned down while walking with two friends at Grange Lodge Avenue in Clongriffin.
Gardai are satisfied that around 90pc of the "fundraising" carried out by the RIRA in Dublin ended up in their own pockets, with the rest handed over to the organisation.
During the summer Ryan had led his group into an alliance with another RIRA faction in Derry as well as two other dissident republican groups to form a new terrorist network.