Two people questioned in connection with the killing of Daniel McAnaspie (17), whose body was recovered from a drain in Co Meath this month, have been released by gardaí.
A file is being prepared for the Director of Public Prosecutions.
Three men who were arrested in the Blanchardstown area on Monday in connection with the murder were released yesterday.
The decomposed body of Mr McAnaspie was found by a farmer on May 13th in a drain between two fields about 200 metres off the old Dublin to Derry road at Rathfeigh, Co Meath.
A postmortem revealed he had been stabbed to death.
Daniel, who was in the care of the Health Service Executive when he was killed, was last seen on the street at Whitestown Avenue, Blanchardstown, west Dublin, on February 26th.
He was living in HSE care in a house in Donabate, north Dublin, and had gone to Finglas to meet people he knew on the afternoon of February 25th.
Investigating officers believe members of the group with whom the youth remained on with were drinking on the road at Whitestown Avenue and in a number of houses into the early hours of February 26th.
Gardaí believe Daniel became involved in a row in Whitestown with men slightly older than him and was fatally stabbed in the throat and upper body.
One of six siblings, whose father died in 1996 and whose mother died in 2007, Daniel could not read or write and had been in the care of the HSE since 2003.