A man has been arrested and another released after a former IRA commander was shot dead in Belfast.
Gerard 'Jock' Davison was gunned down in the street close to his home in the Markets area on Tuesday morning.
The Police Service of Northern Ireland (PSNI) said on Twitter that a 27-year-old man was detained last night, while a 41-year-old man arrested earlier was released without charge.
A 27 year old man has been arrested this evening by Detectives investigating the murder of Jock Davison.— Police Service NI (@PoliceServiceNI) May 6, 2015
A 41 year man arrested earlier today by Detectives investigating the murder of Jock Davison has been released unconditionally.— Police Service NI (@PoliceServiceNI) May 6, 2015
Earlier, detectives appealed for the public to assist the investigation.
Detective Chief Inspector Justyn Galloway said: "I would again appeal to people who were in the Welsh Street area at 9am on Tuesday and who have information about the shooting to talk to detectives at Musgrave police station."
It is understood grandfather and father-of-three Mr Davison, 47, had been making his way to a community centre where he worked when he was attacked.
He was shot a number of times while walking along Welsh Street in the staunchly-republican Markets area close to the city centre.
As the IRA officer commanding in Belfast, he was one of the best-known republican figures in the city.
He backed Sinn Féin's peace process strategy following the 1998 Good Friday Agreement and was employed with the Markets Development Association as a community worker.
He was allegedly involved in the fight that led to the death of Belfast man Robert McCartney in January 2005 and was among three IRA members expelled following an internal investigation in the wake of the death.
He was questioned by police, but released without charge.
Mr McCartney's sisters, who were forced to move out of the Markets, led a long-running battle for justice for the killing of their brother following a bar argument, which took them to the White House.
The killing happened at a time when Sinn Fein was under pressure to accept the rule of law in Northern Ireland.
Its decision to support the police two years later led to the formation of a ministerial executive at Stormont and the sharing of power between republicans and the DUP.
Mr Davison's uncle, Terence Davison, was later acquitted of Mr McCartney's killing.