Ten people are now being questioned about the sectarian murder of a Catholic community worker in Coleraine.
Two other men were released without charge on Tuesday night.
Kevin McDaid, a 49-year-old father of four, was beaten to death yards from his home on Sunday night.
The cross community worker was targeted by a gang of up to 40 men who entered a mainly Catholic housing estate hours after Rangers beat rivals Celtic to the Scottish Premier League title.
It has been revealed that Mr McDaid had been working with police to calm community tensions before he died.
Three people, including a 15-year-old boy, were detained in raids in Coleraine on Tuesday.
They are being questioned about the murder at the Serious Crime Suite in Antrim along with nine arrested on Monday.
A second man, Damien Fleming, 46, is fighting for his life in hospital after being assaulted during the same disturbances.
The mob even turned on the dead man's Protestant widow, Evelyn, when she tried to save him.
After a beating she was left with two black eyes and covered in cuts and bruises.
Murder 'not UDA'
While Mrs McDaid said she believed the murder was the work of the loyalist Ulster Defence Association, a police chief said there was no suggestion the murder was orchestrated by paramilitaries.
Assistant Chief Constable Alastair Finlay said: "There is no evidence this was anything other than a maverick group of yobs. This group made their way down from a pub intent on violence."
He added: "There is no suggestion it was in any way organised by any particular group."
"This was a group of about 15 males who went on a rampage with devastating consequences."
The political representatives of the UDA - the Ulster Political Research Group - issued a statement in which they condemned the murder and those who would seek to cause community tensions.
They added: "There can be no justification for taking of life; there can be no reason or excuse.
"We understand that community tensions in the general area have been running high but appeal for calm and common sense to be exercised.
"We must not leave any stone unturned or leave any excuse for those who would seek to take us back to the past, any opportunity to exploit this community for their own ends."
Tensions
The PSNI said there were tensions in the wake of Rangers sealing the title and people in the Catholic area believed there was to be some sort of parade and "exhibitions of triumphalism" by the loyalist community.
In response there was a building of barricades to keep them out and a raising of flags.
"We achieved, as we understood, a settlement where the barricades were removed, indeed Kevin was part of the removal."
"He was speaking to the community police sergeant only 45 minutes before his death," said Mr Finlay.
Events developed quickly and a maverick group of people moved into the area in response to the flags being put up and, police understood, tried to take them down, he said.
"That led to the group disturbance where Kevin lost his life."
'No retaliation'
A shrine of Celtic football shirts, scarves and flowers bearing messages of sorrow built up at the scene of the murder.
Pinned to a bouquet of carnations was a note from Mrs McDaid. It said: "Kevin. Loving husband and loving father and No 1 Dad. I will always miss you. Your loving wife Evelyn."
Mrs McDaid said her husband would not want to see any more violence.
"He wouldn't want retaliation for it," she said.
"He wouldn't want my sons to get hurt, he wouldn't want this."
Mr McDaid, a former plasterer, had three sons and a foster son. His widow said the family's life had been shattered.
© Press Association