'Tell the truth about Adrian's murder' - gardai
Senior investigators have vowed they will go "to the ends of the Earth" to bring Detective Garda Adrian Donohoe's killers to justice.
The murder gang's identities are known to gardai, and they are living both in Ireland and abroad, including in the US as well the North.
Det Gda Donohoe, a father-of-two, was murdered during an armed robbery at the Lordship Credit Union near Dundalk, Co Louth, on the morning of January 25, 2013.
On the fifth anniversary of the murder yesterday, senior gardai said the killers were being shielded by family and friends.
Chief Superintendent Christopher Mangan said those providing support to Det Gda Donohoe's killers "will never have peace" until they come forward with information about the murder.
"The persons involved in this murder have no doubt received logistical and emotional support from their families and friends," he said.
"And I'm speaking to you in particular, the families and friends of the people who were involved in the murder.
"Your mind will never have peace until you tell the truth of what happened to Adrian. "It's not too late to do the right thing."
Gardai said they had made significant progress in the investigation, and were liaising with police forces globally including the PSNI, UK authorities and US police forces.
No charges have yet been brought over the murder.
A chief suspect is due for release from prison in the coming weeks after being jailed for offences unrelated to Det Gda Donohoe's killing.
The man, who is in his 20s, absconded to the US following the murder but was extradited back to Ireland last year.
Yesterday, Acting Garda Commissioner Donall O Cualain paid tribute to the murdered officer.
"Adrian's ultimate sacrifice to protect others will never be forgotten by his loved ones, the wider garda family, the local community he served so well, and the State," he said.
"He is an enduring example to us all."