Cologne prosecutor Ulrich Bremer said most of those accused in a series of robberies and sexual assaults were in fact refugees.
Mr Bremer said ‘the overwhelming majority of persons fall into the general category of refugees.’
He said 73 suspects have so far been identified, of whom 12 are linked to sex attacks.
Some entered Germany saying they wanted to apply for asylum, while others have formally filed an application.
Among the 15 suspects who are in custody is a Moroccan asylum-seeker who entered Germany in November.
A total of 1,075 criminal complaints have been filed, including 467 alleging crimes of a sexual nature ranging from insults to rape.
Police are also dealing with nearly 700 reported crimes during the week-long carnival in Cologne earlier this month, with more than 400 people taken into custody.
There were around 45 reports of sexual assaults, including one which sparked a fight after a migrant was accused of groping a 19-year-old woman.
More than a dozen people became involved in the brawl after the 36-year-old North African man allegedly grabbed the woman’s bottom.
|Cologne prosecutor Ulrich Bremer said 73 suspects have so far been identified, with 12 linked to sex attacks|
One witness said one of those involved drew a knife.
Police said the number of sexual offence complaints almost quadrupled at this year’s carnival despite heightened security.
A total of 66 complaints for sexual insults or aggression have been lodged compared to 18 such reports the previous year.
More than 2,000 officers had been deployed for the event, which attracted a million visitors.
The migrant crisis was reflected in the carnival floats with one featuring a caricature of Chancellor Angela Merkel in front of her signature quote ‘We will manage it’ and the words ‘tough nuts’.
At her side was a basket of nuts labelled ‘refugees’.
Mrs Merkel’s popularity has slumped after being accused of mishandling the crisis.
She has been criticised for her open-door approach that saw more than a million people claim asylum there last year.