Gardaí have arrested a seventh person in connection with the investigation into the murder in Cork last year of Gerard 'Topper' Stanton.
The operation is targeting the activities of dissident republicans in the city and county.
The man arrested is in his 50s and from Ballinlough in Cork City and is being detained at Mayfield Garda Station under Section 30 of the Offences Against the State Act.
Five men and one woman are now being questioned in what gardai describe as a planned 'intelligence' led operation.
Another man was released without charge from Mayfield Garda Station earlier.
Gerard 'Topper' Stanton was shot in front of his partner and her two young children as he got into his car outside his rented home at Westlawn in Wilton, Cork, last January.
The Real IRA said it shot Mr Stanton, who was a convicted drug dealer, and warned that it would shoot others involved in drug dealing too.
In a statement last November, dissident republicans claimed they had shot five people over the previous year, four of them in the Republic of Ireland.
The people still in custody are being held at the investigation headquarters in Togher and in Mayfield, Gurranabraher and the Bridewell garda stations in Cork.
The suspects can be detained for up to five days.
More than 60 gardaí and detectives were involved in the operation and searches were carried out for much of yesterday.
Gardaí also seized more than 300 rounds of ammunition for an automatic weapon during the operation.
This is the second planned operation against dissident republicans by detectives investigating the death of Mr Stanton.
