The 28-year-old mother of two was gunned down at the doorway to her home in Swords, north Dublin, on November 19, 2006.
Yesterday, on the anniversary of her death, detectives arrested two men, bringing to 18 the number of people questioned in connection with the investigation.
The two were arrested at their respective homes, in Allenwood, Co Kildare, and Coolock, north Dublin.
The Kildare man, who is originally from west Dublin, is considered by gardaí as one of the main importers and distributors of drugs in Ireland.
The men were detained under section 30 of the Offences Against the State Act, and were taken separately to Swords and Coolock Garda stations.
They are being held on suspicion of possession of information in relation to the firearm used in the murder.
Superintendent Mark Curran of Coolock Garda Station appealed directly to gang members with information, who might feel free to come forward, to contact them.
There are people out there, involved in the planning and execution of the murder, and their associates, who have vital information in relation to this. Maybe, their circumstances have changed in the last 12 months and we’re appealing to any of those people to pass any information to us which will be dealt with in confidence.”
Swords Garda Station can be contacted on 6664700.