The PSNI has confirmed that two men have been arrested in connection with the murder in January of Belfast man Robert McCartney.
A PSNI spokesman confirmed the arrests were as a result of police operations in Belfast and Birmingham. The men are understood to be aged 36 and 49.
It is understood the man arrested in Birmingham had been staying at the rented flat in Victoria Road for just three weeks.
A neighbour who lives next door to the second-floor bedsit where the 36-year-old was arrested told reporters he was woken by the sound of police officers battering open a side gate to the property.
The witness, who declined to give his name, said: "When I looked out, the police were round the back with guns.
"There was a big crash and it was a shock seeing two policemen armed. "When I came out into the road they were all lined up with vans and everything.
"I didn't see anybody being led out - there was no shouting and everything appeared to be very calm."
Another resident, Eunice McGhie-Belgrave, said she had not been woken by the police raid.
But she added: "When I looked out of the window at about 7.30 I saw the police were still there and a man in a white suit was examining a car parked in the street."
The McCartney family has campaigned widely for justice for their brother following allegations of intimidation of witnesses in the Short Strand area of Belfast. The campaign gained wide support from political figures in Ireland, the US and the EU.
Robert McCartney was drinking with a friend, Brendan Devine, in Magennis's bar in Belfast city centre on January 30, when a row broke out with republicans, resulting in violence.
He was stabbed and beaten outside the bar and Mr Devine was also seriously wounded.
The IRA condemned the murder and expelled three members for their involvement in the killing and Sinn Fein has also dismissed two of its members for failing to follow party leader Gerry Adams's call for co-operation with the McCartney family.
The party has also suspended other members.
However Mr McCartney's partner Bridgeen Hagans and his sisters Paula, Catherine, Claire, Donna and Gemma have been unhappy with Sinn Féin and the IRA's handling of the incident.