Update 5.22pm

TODAY IS THE fourth anniversary of the killing of Detective Garda Adrian Donohoe.

The 41-year-old father-of-two was shot dead in the line of duty during an armed robbery at Lordship Credit Union in Bellurgan, near Dundalk, Co Louth, on the morning of 25 January 2013.

No one has ever been charged or brought to justice in relation to the incident. The gang of five involved in the attack escaped the scene with just €4,000.

Marking the anniversary of the killing, Garda Commissioner Nóirín O’Sullivan described his death as a “brutal and senseless murder”.

In a statement, O’Sullivan said: “An Garda Síochána is as determined as ever to bring those behind this horrific crime to justice.

Gardaí today were keen to stress the importance of new information, no matter how small, in helping to solve the murder of their colleague.

In the Garda Memorial Garden on the grounds of Dublin Castle this afternoon, Assistant Commissioner Michael Finn spoke of the “callous murder” and said there are people out there who can help them bring these killers to justice.

Chief Superintendent Sean Ward (left) and Assistant Commissioner Michael Finn (right) appealed for the public's help. Source: Michelle Hennessy/TheJournal.ie

No matter what that piece of information is, big or small, it might seem insignificant to you but it could be that crucial piece of information that makes a link for us to help solve this murder.

Over the last four years, investigating officers have carried over 5,600 individual enquiries, taken over 2,500 witness statements and examined in excess of 20,000 hours of CCTV footage. Still, no one has ever been convicted of the garda’s murder and Finn said someone out there could help provide a “vital cog” in the investigation.

Commissioner O’Sullivan earlier paid tribute to Donohoe:

Adrian was the epitome of all that is good about An Garda Síochána. In his professional and personal life he was dedicated to the community he served. Whether it was his work in Dundalk Garda Station or giving his time to coach underage teams at St Patrick’s GAA in Lordship, Adrian was always focused on helping and supporting others.

“Today, our thoughts are with Caroline, the children, and all of Adrian’s extended family and friends.”

The Irish League of Credit Unions, which represents credit unions in the Republic of Ireland and Northern Ireland, has offered a reward of €50,000 for information that leads to any arrest and prosecution in respect of the murder.

Anyone with information in relation to the murder is asked to call the incident room in Dundalk Garda Station on 042 938 8470 or the Garda Confidential Line number on 1800 666 111.