The Garda Commissioner says the investigation into the murder of Adrian Donohoe will continue until the perpetrators are brought to justice.

Family and friends of the late Detective Garda turned out to attend a special memorial service in Dundalk in county Louth earlier this evening to mark the first anniversary of his murder.

The 41 year old was shot dead outside the Lordship Credit Union in Co Louth in January 2013.

Martin Callinan says Gardai know the identities of those who carried out the attack - but he is appealing to anyone with information to come forward.