A woman has been arrested by police investigating a murder linked to IRA members.
The suspect, 50, was detained in Belfast in connection with the fatal shooting of Kevin McGuigan in Belfast last month which has brought the powersharing institutions in Northern Ireland to the brink of collapse.
Three men including Sinn Fein northern chairman and alleged former head of IRA intelligence Bobby Storey are still being questioned by detectives, the Police Service of Northern Ireland (PSNI) said.
Senior officers have said the murder of Mr McGuigan was not sanctioned by the IRA, but one major line of inquiry is that members of the Provisional IRA were involved.
It is alleged to have been carried out in retaliation for the murder of another former IRA prisoner, Gerard "Jock" Davison, at his home in the Markets area of Belfast in May.
Mr Storey was one of three men, aged 45, 58 and 59, who were arrested in Belfast on Wednesday morning as part of the police investigation. He is a former IRA prisoner.
The other two, Eddie Copeland and Brian Gillen, are also well-known republicans.