Lyra McKee's partner says seeing the gun used to murder her was like "a punch to the gut".
Police confirmed on Thursday that a gun found during searches in Londonderry last weekend was the weapon used to kill Ms McKee.
Ms McKee, 29, was shot during trouble in the city's Creggan area in April 2019.
Her partner, Sara Canning, said she hoped the discovery of the gun will help find the journalist's killers.
Ms Canning said it was "really difficult" to look at the murder weapon.
"It's strange to think something so small caused so much damage and took so much away," she told BBC Radio Foyle.
She had been at work when the pictures came through to her but had had to go home.
Seeing it, she said, "brought it all home".
"Lots of things as we've walked on this path have been like punches to the gut, but that was a particularly big one," she said.
The Police Service of Northern Ireland (PSNI) said Thursday's announcement was "a significant moment for the investigation" into the New IRA murder.
Initial tests and an examination of the weapon, a Hammerli X-Esse pistol, confirmed it was the gun used to murder the journalist.
The gun, along with a bomb, was found during planned police searches in the Ballymagroarty area of Derry.
Ms Canning said she hopes the discovery of the gun will help find her killer.
"We have to hold out hope that is going to give up something that will bring us a step closer to getting the person who fired the gun," she said.
One man, Paul McIntyre, 52, from Kinnego Park in Derry, has been charged with Ms McKee's murder.
He denies the charge.
'New avenue of investigation'
On Thursday police said they hoped the discovery would help them to bring the person who fired the shots to justice.
Det Supt Jason Murphy said "a very detailed forensic examination of the gun, ammunition and the plastic bags in which they were wrapped is currently ongoing".
He said forensic work would take "some considerable time to complete, particularly because of the intricate examination of the internal mechanisms".
He said that the gun had "jammed as the gunman fired" and he had asked scientists to "extend their forensic examination beyond the outside of the gun and forensically examine the inside mechanisms of it".
Mr Murphy said that since 18 April last year, the PSNI had been "collectively focused on seeking to bring to justice those who were involved in Lyra's murder".
"That collective effort has never been simply directed towards the person who pulled the trigger," he said.
"I am as clear today as I have ever been that the bringing of that gun onto the streets involved a number of senior figures in the New IRA.
Mr Murphy said the police investigation also extends to the disappearance of the weapon after it was fired.
New IRA's disregard 'staggering'
"Somebody was able to transport this gun and its ammunition from Creggan to Ballymagroarty and hide them in a field, within 250 yards of local housing," he added.
"This placed other members of the public at further considerable risk.
"The disregard shown by the New IRA is staggering but completely unsurprising.
'I know who the gunman is'
Det Supt Murphy also said they had "appealed for the local community to continue to help my investigation".
"For those with a conscience, Lyra's murder will have played heavily on their minds every single day," Mr Murphy added.
"As the net gradually tightens, those who fired the gun, transported it, moved it, stored it, carried it, hid it or interacted with it in any way, should expect the police at their door.
"Our collective efforts have lost no energy or focus.
"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 18 April that I have been building for Lyra's family since the night she was murdered."