A prison officer shot dead on a motorway in Northern Ireland has been named as David Black by Justice Minister David Ford.
Mr Black, who had spent more than 30 years in the prison service and was nearing retirement, was ambushed on a stretch of the M1 between Portadown and Lurgan, Co Armagh on Thursday morning. One unconfirmed report claimed a gunman opened up when another car pulled up alongside.
It is understood the officer's car careered off the road when he was fired on and he died later.
Although no organisation has admitted responsibility, security chiefs believe republicans opposed to the peace process were involved.
The extremists have been involved in long-running protests against jail conditions inside Maghaberry.
A car understood to have been used in the attack was later found burned out in Lurgan where supporters of dissidents have backed the jail protest campaign.
Police Service of Northern Ireland Chief Constable Matt Baggott said: "It was a completely senseless attack. It demonstrated the recklessness and ruthlessness and sheer dangerousness of those who oppose peace and are dedicated to taking us back to those dark days of the past.
"This has all the hallmarks of dissident republicans. This was just a brutal attack and we need the public's support to be able to solve it as quickly as possible.
"David was dedicated, a person keeping people safe, and we need to respect that and recognise that."
Finlay Spratt, the head of the Prison Officers' Association, knew Mr Black.
"I found him to be a very nice fellow to work with," he said.
"He always ensured he did his job to the letter. He was a very good officer, he certainly did his bit."
Mr Spratt criticised the security provisions offered to prison officers since the Troubles ended.
"They have stripped away all the security around prison officers," he said. "They treat us now as if we live in normal society."
Stormont first minister Peter Robinson and deputy first minister Martin McGuinness also condemned the murder.
"At this time, our thoughts and prayers are with the bereaved family and we condemn this murder in the strongest possible terms," they said in a joint statement.
"There can be no justification for this brutal attack as this man was going about his daily life. People who work for the Prison Service play a crucial role in our community and any attack on them is an attack on all of us.
"Actions like this have no place in society and those who carried out this murder have nothing positive to contribute, and we refuse to let the people behind this attack divert us from building a better and peaceful future for everyone.
"We appeal to anyone with any information on this murder to contact the PSNI."
The shooting happened at around 7.30am, at the same time as a major security alert further along the motorway at a shopping centre at Sprucefield, near Lisburn, where bomb disposal experts were called in to check a car.
It is believed this vehicle might have been linked in some way to the shooting, according to some sources.