Detectives investigating the IRA murder of Belfast mother-of-ten Jean McConville more than 40 years ago have made two more arrests.
Two women, aged 57 and 60, were detained by officers from the PSNI's Serious Crime Branch this morning and have been taken to Antrim police station for questioning.
The abduction, murder and secret burial of Mrs McConville in 1972 is one of the most notorious incidents of the Northern Ireland Troubles.
Nobody has ever been charged with her murder.
After decades without significant developments in the criminal investigation, there have now been six arrests within a month.
In March, veteran republican Ivor Bell was charged in connection with the killing.
Mr Bell, 77, from Ramoan Gardens in west Belfast, faces counts of aiding and abetting the murder and of IRA membership. His lawyer has said he will contest the charges.
Two other 57-year-old women and a 56-year-old man, arrested separately in west Belfast this month, were released from custody after questioning.
Police are preparing reports on both those women for assessment by prosecutors.
Mrs McConville, a widow, was dragged away from her children in her home in the Divis flats, west Belfast, by an IRA gang of up to 12 men and women after being accused of passing information to the British Army in the city.
An investigation later carried out by the Northern Ireland Police Ombudsman rejected the claims that she was an informer.
Mrs McConville was shot in the back of the head and buried 50 miles from her home. The IRA did not admit her murder until 1999 when information was passed to gardaí.
She became one of the so-called Disappeared, and it was not until August 2003 that her remains were found on Shelling Hill beach, Co Louth.