Cologne police say a fourth man has been taken into custody after they released a series of photos of people suspected of sexual harassment and assaults in the city on New Year's Eve.

Police said Friday a 20-year-old Iraqi went to a police station in the western town of Werl on Thursday evening, accompanied by his father, and told officers he was one of the suspects.

The thefts and assaults on women near Cologne's main station, blamed largely on foreigners, heightened tensions over Germany's welcoming of asylum-seekers.

On Tuesday, authorities released five pictures of suspects who allegedly sexually harassed or insulted their victims and attempted to rob them. They were taken by witnesses and victims. Two of the men turned themselves in and a third was arrested following tip-offs.