Two men arrested over the 1991 murder of Donegal Sinn Fein politician Eddie Fullerton have been released.
As part of a cross-border operation yesterday morning, PSNI officers swooped on a house in Londonderry and made an arrest.
The man was taken to Antrim PSNI station's serious crime suite to be questioned about the murder.
The arrest was made in the mainly loyalist Drumahoe area of the city's Waterside by detectives from the PSNI's Crimes Operation Department following a request from the Garda and in consultation with the Historical Enquiries Team.
A second arrest was made by the PSNI on Tuesday afternoon.
They were the first two arrests made by police investigating the murder 18 years ago.
Last night a police spokesman said the two men had been released unconditionally.
Mr Fullerton's daughter, who has led the campaign to bring her father's killers to justice, welcomed the first arrests.
She told the Derry Journal: “It's movement in the case; it's a development and it's the first arrests in relation to the murder of daddy in the 18 years since he was killed.
“The investigation in the weeks, months and years following dad's murder went nowhere. The family has always felt that, had dad been a councillor for any other party, the killers would have been brought to justice.
“These are the first arrests — no one has ever been formally questioned about it in the 18 years since it happened.”
The Fullerton family has consistently claimed that there was state collusion in and a subsequent cover-up of the 1991 murder.
The 56-year-old was shot at his home in Cockhill Park, Buncrana, Co Donegal, as he confronted his killers on May 25 1991. The assassins smashed their way into his home using a sledgehammer. The killing was later claimed by the UDA/UFF.
Sinn Fein MP Martin McGuinness added: “Despite all of the blockages to justice, the Fullerton’s have maintained their dignity and brought their campaign for the truth to every forum in Ireland and beyond.
“Sinn Fein will continue to stand shoulder to shoulder with the Fullerton family and provide them with every support and encouragement.”