A man is due to appear before Belfast magistrates this morning to face charges in connection with the murder of Robert McCartney.
A second man is also expected to be charged in relation to the attempted murder of Brendan Devine, who was seriously injured in the attack outside Magennis's bar in the city centre in which Mr McCartney was stabbed and beaten to death.
The charges follow the arrest earlier this week of two suspects in Belfast and Birmingham.
According to the PSNI, one of the men is 49 and will be charged with Mr McCartney's murder. The other is 36 and will face a charge of attempted murder relating to Mr Devine.
Mr McCartney (33) worked as a forklift-truck driver and was the father of two children.
Although spokesman "P O'Neill" denied in February any Provisional IRA involvement in the murder, the organisation later expelled three of its members and offered to shoot others it said were involved.
Sinn Féin also expelled seven of its members and announced an inquiry.
Mr McCartney's sisters and his partner, Bridgeen Hagans, who have alleged widespread intimidation and accused republicans of a cover-up to protect the guilty, said they were hopeful of a breakthrough in the case.
Catherine McCartney said last night: "We hope it will lead to further arrests because there were more than two people involved. We still have a long way to go in terms of a trial and convictions. We are happy this has happened, but we know it is by no means over."
On Thursday the PSNI sounded its most optimistic to date in relation to the case.
At a public meeting of the Policing Board in Derry, Chief Constable Hugh Orde said the arrests of two people demonstrated what he called "our absolute commitment to bring this to a judicial conclusion". He continued: "It's what we want, it's what the family want. It will be in accordance with the law."
Before Wednesday's arrests, the PSNI had detained 13 people in relation to the murder of Mr McCartney and the attempted murder of Mr Devine, but all had exercised a right to silence and were released without charge.
The office of the Police Ombudsman, Ms Nuala O'Loan, helped 10 people, who were unwilling to approach the PSNI directly, to prepare statements which could be admissible in court.
There were about 70 people in the pub on January 30th when a row broke out. The disturbance continued in a laneway adjacent to Magennis's, and Mr McCartney was fatally injured.
Initially, however, no witnesses came forward. Vital forensic evidence, including a video tape from a CCTV camera on the premises, was removed.
The family have accused the IRA of shielding the killers and claimed as many as 12 members were involved in the subsequent cover-up.
It emerged that Sinn Féin election candidates had been in the bar at the time the disturbance broke out.
Cora Groogan, a party candidate in Mid-Ulster in 2003, said she was in Magennis's bar but saw nothing.
Another Sinn Féin member, suspended pending a party investigation of the case, announced in April she would not contest the local government election on May 5th; Deirdre Hargey had been selected to run in Belfast's Laganbank as one of two Sinn Féin city council candidates.
The party subsequently lost a seat to Alliance in the area which includes Short Strand where Mr McCartney lived.
The McCartney sisters and Ms Hagans have travelled extensively as part of their "Justice for Robert" campaign.
They have met both governments and in March were welcomed to the White House by President George Bush.
The European Parliament has voted to support a civil action against those who the sisters believe were involved, should a criminal case fail.
European Parliament president Josep Borrell said he was confident money would be made available.
He added: "There hasn't been a precedent, but you have to start somewhere. It's important for people to speak out."