Cologne prosecutor Ulrich Bremer says 73 suspects have so far been identified, of whom 12 are linked to sexual assaults.
He says recent reports describing only three of the suspects as refugees are "total nonsense."
Bremer told The Associated Press today that "the overwhelming majority of persons fall into the general category of refugees."
Some entered Germany saying they wanted to apply for asylum, others have formally filed an application.
Among the 15 suspects who are in custody is a Moroccan asylum-seeker who entered Germany in November.
