MIT detectives supported by a team from the Tactical Support Group swooped this morning in Craigavon and arrested a 42-year-old man.
He was taken by car to the custody suite at Musgrave PSNI station to be processed for interview about the attempted murder.
Police say the suspect has now been released on bail pending inquiries.
The victim, Martin Gavin, was critically injured when he was shot in the head as he sat in a Vauxhall Zafira car with his partner in Rossnareen Avenue on Thursday, November 19, 2015.
Police say he remains in hospital with “life changing injuries”.
Detectives believe two men were involved in the attack and are appealing for information.
Detective Inspector Peter Mullan said: “We believe the two men came out of a vacant house in Rossnareen Avenue wearing high visibility workmen’s jackets.
“One of them approached the victim’s car and opened fire with what we believe to have been a shotgun.
“They made off in a silver Honda Civic car which was abandoned a short distance away in Inishmore Crescent.
“The victim remains in a critical condition in hospital and has sustained life changing injuries.
“This was a ruthless and reckless attack in a busy street at a busy time of the day.
“I am appealing to anyone with information about the incident, the two men or the silver car to come forward.
“They can contact detectives at Musgrave police station on the non-emergency 101 number, or can provide information without giving their details to the independent charity Crimestoppers on 0800 555 111.”
Two men, aged 18 and 50, have appeared in court charged in connection with the overall investigation into this incident.
They have been accused of making threats to kill.