Drazancic told Hina the youth was released, among other things, also because the prosecution did not request that he be remanded in custody.
She said the unemployed 19-year-old's name was Branko Brlekovic and that he gave up the right to an attorney.
The judge said Brlekovic was arrested on Friday evening on charges of spreading false and disturbing rumours.
Brlekovic sent some Croatian media and state institutions threatening letters allegedly by "The Raid on Politicians" terror network on three occasions over the past month. This crime entails a fine or imprisonment up to six months.
Drazancic declined to speak about Brlekovic's statement, why he wrote the threatening letters in the name of a fake terrorist group, or evidence which the police and the prosecution have against him.
Earlier today, the police quoted the teenager as saying that he sent the threatening letters because he enjoyed unsettling the public and the fact that they received extensive media coverage.