Hundreds of republicans are expected to attend the funeral of murder victim Gerard 'Jock' Davison due to take place on Saturday.
The 47-year-old was shot dead on Monday morning as he walked to work in the Markets area of Belfast.
A 27-year-old, named locally as Scott McHugh, was arrested by detectives on Wednesday investigating the murder of the former IRA commander. Searches of properties in the Markets area of south Belfast were also carried out.
Brendan Devine (41) - a close friend of Robert McCartney who was murdered in 2005 - had been arrested in north Belfast on Tuesday but was later released unconditionally.
There is expected to be a heavy police presence for the funeral on Saturday which clashes with a UVF memorial parade that passes close to the Markets. It is expected to be attended by 15,000 loyalists and 76 bands.
The parade is travelling from north Belfast to east Belfast, through the city centre and close to the Markets.
A former member of the IRA's 'northern command' the remains of Mr Davison, who was an atheist, will go straight to Milltown cemetery from his partner's house in Friendly Street in the Markets without any Requiem Mass.
The father-of-three was shot several times in the head and chest as he walked to work at about 9am on Monday in Welsh Street.
A close relative of a man murdered by the IRA in the early 1990s is believed to be the chief suspect.
Sources say detectives believe the murder weapon to be hidden somewhere within the Markets area. The killer is also thought to have had local knowledge and escaped on foot with no getaway car used in the murder.
Police have said the murder was not carried out by dissident republicans but by criminal elements who harbour a grudge against Mr Davison.
During his time as the most senior IRA man in Belfast the organisation was responsible for a number of murders of people deemed to be high profile criminals using the cover name Direct Action Against Drugs.
Senior republicans Colin Duffy, Alec McCrory and Harry Fitzsimons sent "deepest sympathy and sincere condolences to the immediate and wider family of Jock"
The three are currently on remand on the republican wing of Maghaberry prison charged with an attack on police in north Belfast in December 2013.
It follows on from a statement from Republican Network for Unity who also condemned the murder and sent sympathies to the Davison family.
