Brian Shivers was arrested on Tuesday evening
A 44-year-old man has appeared in court in Ballymena charged with the murders of two soldiers and the attempted murder of six other people.
Brian Shivers, from Maghera, was also charged with firearms offences.
Sappers Mark Quinsey, 23, from Birmingham, and Patrick Azimkar, 21, from London, were shot dead at Massereene Army base, Antrim, in March.
Police have said they fear another man being sought over the murders may have left Northern Ireland.
"We have previously tried to arrest another suspect in this investigation, but have been unsuccessful, and we have reason to believe he has fled the jurisdiction," Detective Inspector Justin Galloway said.
Mr Shivers, who is also accused of possession of firearms and ammunition with intent to endanger life, was refused bail and remanded in custody.
Ballymena Magistrates Court was told CCTV cameras recorded pictures of two masked gunmen firing 60 rounds of ammunition during the attack.
Detective Inspector Galloway told the court there was DNA evidence linking Mr Shivers to the alleged getaway car.
He said it had been discovered on a mobile phone and on items found inside and outside the vehicle.
A defence solicitor questioned the validity of the evidence and said they were just partial matches.
Sappers Patrick Azimkar and Mark Quinsey died in the Real IRA attack
However, Magistrate Phillip Mateer said while the merits of low-copy DNA had been debated during the trial of Omagh bomb suspect Sean Hoey, the court still accepted it as evidence.
The soldiers were killed by the Real IRA outside the barracks as they collected pizzas they had earlier ordered.
Two gunmen in a car parked nearby opened fire with semi-automatic rifles.
Four other people were seriously injured, including the pizza delivery men.
Prominent dissident republican Colin Duffy is the only other person to have been charged with the murders.