Detectives are continuing to question two men today in connection with the murder of Robert McCartney.
Armed officers smashed down a door to seize one of the men in an early morning raid at a bedsit in Birmingham yesterday.
A second man was detained in Belfast as part of an arrest operation which relatives believe could signal a major breakthrough in the police investigation.
Mr McCartney, 33, from the Short Strand area of Belfast, was murdered by IRA men after being dragged from a city centre bar four months ago.
The two arrested come from the neighbouring Markets area but one had been staying in Birmingham for the past three weeks.
The man, 36, was wearing just his boxer shorts when police burst in to his second-floor bedsit in the Stechford area of the city.
Eyewitnesses described how he was led barefoot to a waiting police car in Victoria Road.
He was flown back to the North for questioning by a team of detectives headed by Inspector Kevin Dunwoody.
The other man, aged 49, was arrested in Belfast.
Police yesterday confirmed the two men can be held for questioning at Antrim for 72 hours.
Mr McCartney died after he was beaten and stabbed outside Magennis’s Bar in Belfast city centre on January 30.
His sister, Catherine McCartney, said she hoped the arrests would signal a major breakthrough in the investigation.
No one has yet been charged in connection with the murder, even though key suspects and several customers who were in the bar at the time have been interviewed.
Mrs McCartney said: “We obviously welcome these arrests but remain cautious.
“People have been arrested before and let out.
“Others have walked into police stations, stared at walls and said nothing.”
It is understood the man arrested in Birmingham had been staying at the rented flat in Victoria Road for just three weeks.
Senior members of the IRA in the Markets and Short Strand areas, where Mr McCartney lived with his partner and two children, are believed to have been involved in the murder, which led to the Provisionals expelling three men.
Several Sinn Féin members have also been suspended and some thrown out of the party.