A gun found by police during searches in Londonderry is believed to be similar to the one used in the New IRA murder of Lyra McKee.
The weapon is being forensically examined to establish if it was the gun used.
Police have said a bomb also discovered during the searches was fully primed for an imminent attack.
Ms McKee, a 29-year-old journalist, was shot during trouble in the city's Creggan area in April 2019.
The gun, along with the bomb, was found during planned police searches in Derry on Friday and Saturday in the Ballymagroarty area of the city.
Search operations took place over two days, and covered 38 acres.
'Encouraging line of enquiry'
Derry City and Strabane district commander Ch Supt Emma Bond said the gun was the same type and calibre used to murder Ms McKee and that extensive forensic examinations would be taking place in the coming days and weeks.
She said:"Whilst we regard this as an encouraging line of enquiry, I will repeat that we cannot definitively say at this time whether or not this is the murder weapon," she said.
"That determination will be guided by the forensics."
Ch Supt Bond added: "We were able to locate and safely remove a command-wire initiated bomb, a handgun and a quantity of ammunition.
"A strong line of enquiry is that these munitions belong to the New IRA.
"They have now been seized and will be subject to rigorous forensic examination in the coming days and weeks.
"The fact that these items were left close to a populated area, and particularly on land where children are known to play, yet again underlines the total lack of regard these violent terrorist criminals have for their own communities," she said.
"These people are so singularly focused on murdering police officers that they do not care if others - men, women, children, families - are caught up in their evil plots.
"The community is simply collateral damage."
Chief Constable Simon Byrne described the find as a "major breakthrough," adding it was a "reminder that a small number of people with no community support or mandate are still determined to wreak havoc, destroy lives and devastate families".
Earlier in the year Paul McIntyre, 52, from Kinnego Park in Derry was charged with Ms McKee's murder, which he denies.
Speaking on the first anniversary of her death, Det Supt Jason Murphy said there were up to 17 suspects in the investigation.