A father of one has been sentenced to 10 years for his involvement in an armed raid on a credit union during which a gun was pointed at a garda and a car was hi-jacked.

Sean Donnelly (20) whose father is serving a life sentence for murder, stood at the door of the credit union in Portmarnock while his accomplice, Derek Murphy (45) threatened two members of staff and a customer with a hand pistol.

The three women were all terrified and believed that Murphy was going to shoot them. He pointed it at the customer’s legs, while the staff were sure the weapon was going to go off because it was being waved around so much.

The court heard that Donnelly was trying to get Murphy to calm down.

Garda Michael Bolton, who chased after the raiders on his bicycle, was threatened by Murphy with the gun. Murphy pointed the gun at him and shouted at him “to get the fuck back” but the garda continued the pursuit, later abandoning his bicycle.

He then spotted the pair run up to a car and shout at the woman in it to get out. The gun was then turned on him again and Gda Bolton ducked for cover behind a nearby vehicle when he heard it being fired.

Murphy and Donnelly hi-jacked the car and Gda Bolton waved down a passing motorist. The garda got into the passenger seat of the vehicle and directed the driver to follow the stolen car.

He later lost sight of the car and other officers got involved in the chase. The robbers were tracked down when the car ultimately crashed near the Belmayne Road in Clongriffin.

Donnelly was on bail two years later when he and two accomplices robbed a cash box containing €40,000.

He was arrested within minutes when he was spotted running through a nearby housing estate, with another man who was carrying the cash box.

Murphy of Springdale Road, Raheny has admitted some of the offences in relation to the credit union raid and is due for sentence later.

Donnelly of Belcamp Crescent, Priorswood pleaded guilty at Dublin Circuit Criminal Court to robbery of €2,900 from Portmarnock Credit Union, possession of a firearm and hi-jacking on November 16, 2012.

He also pleaded guilty to robbery of the cash-in-transit worker at Clarehall Shopping Centre, on the Malahide Road, Dublin 17, on April 26, 2014.

Donnelly has 43 previous convictions for road traffic, drug and public order offences as well as a charge for possession of a firearm when he was 14 years old.

Judge Martin Nolan said it was clear that Murphy terrified everyone in the credit union and Gda Bolton who he said “very bravely” followed the raiders.

He said the owner of the vehicle that was used to make their escape was also put in fear.

Judge Nolan accepted garda evidence that Donnelly is respectful in their dealings with him and has been well behaved while in custody but added “when left to his own devices he allows himself to get involved in criminality”.

He sentenced Donnelly to consecutive sentences totalling 10 years before he suspended the final three years of that term on strict conditions.

Patrick Marrinan SC, defending said Donnelly was first convicted at 14 when he was caught holding a gun for someone else. He received a sentence and was sent to Oberstown Detention Centre.

Counsel said his client’s father, Peter, then became obsessed with “seeking revenge on those who had taken advantage of his son” and started to keep a local park, where he believed drugs were being stashed, under observation.

During this time he came across a gun. He never reported it to gardaí and brought it home and hid it.

Some time later, in an unrelated incident, he had a row with his friend during a party in his home. He got the gun and shot the man, killing him. He was later sentenced to life.

Mr Marrinan said his client was extremely close to his father and this had a huge impact on him.

Garda Shane McGrath told Anne Rowland BL, prosecuting that Gda Bolton spotted the raiders from the credit union robbery running into a nearby housing estate after the raid and, thinking they were supicious, chased after them on his pedal cycle.

Murphy pointed the gun at him and shouted at him “to get the fuck back” but the garda continued the pursuit, later abandoing his bicycle.

He then spotted the pair run up to a car and shout at the woman in it to get out. The gun was then turned on him again and Gda Bolton ducked for cover behind a nearby vehicle when he heard it being fired.

The pair managed to hi-jack the car and leave the scene. Other members of the force were called in and the owner of the car provided her registration details.

Murphy and Donnelly were spotted hiding near an embankment. When they saw gardaí they ran off and Donnelly managed to scale a fence to escape. Murphy was arrested when he couldn’t get over the fence.

The gun and the cash were recovered nearby in a jacket and pair of tracksuit bottoms. Donnelly was arrested two days later.

He later told gardaí Murphy knocked at his door that day and told him he owed him a favour. He said he didn’t want to let him down and accepted that his girlfriend dropped them off at the credit union.

He claimed he didn’t know Murphy had a gun until he got to Portmarnock.

Garda Alan Flaherty said a cash box containing €40,000 was robbed from a security worker after a man jumped out of a car, carrying a hammer and shouted at him to “give me the box”.

The robber jumped back into the waiting car and the driver sped off in the direction of the Malahide Road.

A nearby taxi driver noted the registration number of the getaway car and provided gardaí with a description of the robbers.

Donnelly was spotted minutes later running towards a house in a nearby estate. He was wearing the same clothing as had been described and was arrested.

He told gardaí in a subsequent interview that his mother owed €3,000 in rent and that’s why he got involved in the robbery.

There was no evidence that he was the driver of the getaway vehicle.