Gardaí in Co Wexford are holding four people in connection with the disappearance of a 19-year-old woman more than seven years ago.
Three of the detainees - a man and woman in their 30s and a woman in her 50s - were arrested at their homes in the Wexford area this morning, while the other - a man in his 30s - was arrested last night.
Gardaí said another woman in her 30s was also detained as part of the same investigation last night, but was later released without charge.
The four still in custody are being questioned about the disappearance of Fiona Sinnott from her home in Broadway, Co Wexford, in February 1998.
Intensive searches at the time failed to turn up any trace of the missing mother-of-one.