The Provisional IRA is responsible for the £26.5m (€37.7m) bank raid on the Northern Bank in Belfast city centre before Christmas, Chief Constable in the North Hugh Orde has said.
He said that media interest in the case and pressure to attribute the crime would not distract the Police Service of Northern Ireland from their inquiry.
He said he was confident the IRA was behind the crime and that he was making that statement so that the inquiry could move on. "In my opinion, it is the Provisional IRA which is responsible for this crime," he said, adding that all lines of inquiry led in that direction.
"This was not a victimless crime. Two families were put through a great deal, including being threatened with death. This was a very violent and very brutal crime. It was not a Robin Hood effort."
Some 45 detectives are investigating the case. One hundred interviews have been completed, with about the same number planned.
"Our main focus is to catch those responsible," said Chief Constable Orde. He added that this was "one of the biggest investigations" every undertaken in the North, with national and international implications.