Gardaí have freed two of the four people being questioned over the death of Swiss student Manuela Riedo (17) who was found murdered near Lough Atalia in Galway city last week.
A woman and a man, who were being questioned at Gort and Loughrea Garda stations, were released tonight without charge. Files are to be sent to the Director of Public Prosecutions.
Two men are still being held at Galway Garda station.
Two men and a woman were arrested as part of a planned operation in Salthill just after 7.15am today. Another man was arrested around two hours later. All are in their mid-to-late 20s.
One of the men is understood to have been arrested in connection with the murder and is known to the gardaí. Two others were arrested on suspicion of withholding information.
Ms Riedo was found strangled to death near a walkway on the shore of Lough Atalia near Ceannt train station.
Divers began looking for clues today around the bridge near where Ms Riedo was found in dense growth on pathway between Renmore, where she was staying, and Ceannt station on Tuesday October 9th.
Detectives searching through records of offenders in the city with a history of assault and sexual assault believe they have made a breakthrough in the inquiry.
Minister for Foreign Affairs Dermot Ahern has asked the Irish ambassador to Switzerland, James Sharkey, to represent the Government at the student's funeral tomorrow in the Swiss capital Bern.
Mayor of Galway Tom Costello, city manager Joe McGrath and representatives of three of the city's language schools will also attend the ceremony near Ms Riedo's home in the suburb of Hinterkappelen.
Beverly Bazler, director of the Galway Language Centre where Ms Riedo had been enrolled to study, is bringing books of condolence, along with several hundred Mass cards left into the centre by people from Galway.
A spokesman for the centre said Ms Bazler hoped to meet Ms Riedo's parents.
Ms Riedo's host family in Renmore, Galway city councillors, students and members of the public are to attend a special service for Ms Riedo in Renmore parish church tonight at 7.30pm.
Additional reporting PA