Two people - a man and a 16-year-old girl - who were being questioned by gardaí about the murder of Daniel McAnaspie were released without charge overnight.
A file is being prepared for the Director of Public Prosecutions.
Three men who had also been questioned were released yesterday without charge.
The body of Daniel McAnaspie was discovered in a field in Rathfeigh, Co Meath, earlier this month.
A post mortem established that he had been stabbed to death.
The Dublin teenager had been missing since 25 February.