The report, details of which were widely published by German media today, added to witness accounts describing a string of sexual assaults that have sparked a heated debate about migration and the police's failure to prevent the mayhem.
Chancellor Angela Merkel said Germany must examine whether it has done enough to deport foreigners who commit crimes, after police said the perpetrators of the attack were of "Arab or North African origin."
"We must examine again and again whether we have already done what is necessary in terms of ... Deportations from Germany in order to send clear signals to those who are not prepared to abide by our legal order," Merkel said.
She described the New Year's assaults as "repugnant criminal acts that ... Germany will not accept," and said changes to the law and increasing police presence may be examined.
German daily Bild today published extracts from an unidentified senior federal police officer's report on the attacks.
It recounts how federal units, who are also in charge of policing the railway system, were met by "anxious citizens with crying and shocked children" when they arrived at Cologne's main railway station on New Year's Eve.