Detectives investigating the rape and murder of Lorraine McCausland, who was found beaten to death after a night out in a loyalist club 30 years ago, said a file will now be sent to the PPS about the crime.
Yesterday police said two men, aged 54 and 56, had been detained in Belfast in connection with the case and another two were held in Antrim, aged 53 and 59.
About 24 hours earlier three men were arrested in Great Britain – two in Scotland and one in England.
Late last night the PSNI said all seven men arrested have been released, and that a file will now be submitted to the PPS.
Mother-of-two Ms McCausland, 23, was found beside a stream in the Forthriver area of north Belfast in the early hours of March 8, 1987.
She was last seen in a loyalist club nearby.
The case was re-opened last year after detectives identified “potential new lines of inquiry”.
Fourteen arrests were made during the original police investigation but no-one was charged.
Members of the UDA were suspected of killing her. Police believe witnesses have long been fearful of coming forward due to the involvement of the group.
The victim’s son, Craig, was murdered in north Belfast in 2005 during a spate of killings linked to a loyalist paramilitary feud.