Police have recovered the gun used to murder Lyra McKee in Derry.
Investigators believe it may have been stolen some time ago and used a number of times before journalist Ms McKee was shot in April last year.
The Hammerli X-Esse .22 pistol and a bomb were found during searches in the Ballymagroarty area of the city last week.
"I can confirm that a gun that was seized and recovered by police last week in Derry was the gun that killed Lyra Mc Kee," Police Service of Northern Ireland (PSNI) Detective Superintendent Jason Murphy said.
Ms McKee was an observer during rioting in the city's Creggan area.
Det Supt Murphy said the shot that killed her was fired in the direction of officers.
He said senior members of the New IRA were involved, adding: "For the IRA, the net is tightening."
Search operations that recovered the weapon from a field within 230 metres of houses took place over two days.
Police said it was a significant moment.
"Last night, I had the unenviable task of telling Lyra's family and her partner Sara that after months of painstaking work, the gun that killed Lyra has been removed from the terrorists' control," Det Supt Murphy added.
"Understandably, they are relieved that no other family will ever have to face the devastation arising from the use of that gun, that they have been forced to face for the past 15 months.
"This is also a very difficult moment for all of them as they struggle every day to deal with Lyra's brutal murder."
One man, Paul McIntyre (52), of Kinnego Park, Derry, has been charged with Ms McKee's murder.
The 29-year-old's death helped kick-start political talks leading to the resumption of Stormont power-sharing early this year.
Det Supt Murphy said the weapon jammed as the gunman fired it and footage showed him trying to eject the rounds.
The detective added that the most advanced DNA technology available was being used to examine whether the gunman may have left forensic traces within the weapon.
"Our collective efforts have lost no energy or focus," Det Supt Murphy said.
"I know who was involved. I know who the gunman is.
"I have asked the scientists to find me the evidence that will enable me to complete the jigsaw of the events of April 18 that I have been building for Lyra's family since the night she was murdered."