Canadian Expat in Germany:
I live one city over from Cologne and spoke with an eyewitness to this event who was there on NYE celebrating with friends. She works with the homeless, and I have no reason to believe that she is a right leaning radical person. She said that small groups of women were encircled by groups of men who wouldn't let them pass, and then proceeded to insert their fingers into the women's vaginas and/or anuses (this is the "groping" that the mainstream media refers to). They were then robbed. She indicated that there was a predominant ethnic group involved in these acts.
Local social media was abuzz about these violent sexual assaults, but mainstream German media shied away from picking up the story up right away. Apparently women went to the police and in at least one case were told that they could file the complaint about their belongings being stolen, but not about having been sexually assaulted. German politicians were slow to speak up, and when they initially did they scapegoated the local police instead of speaking up to take a strong stand against violence against women. We have yet to see Merkel hold a press conference and reassure her nationals, who appear to be scared and angry.
To make matters worse the Mayor of Cologne, a woman, went live on air telling young women that they should make sure they stay at arm's length from men to protect themselves, implying both that it was the victims' fault, and that the government has lost control over central Cologne, at least if you are a young woman. Her comments have caused an international outcry on social media.
I don't want to get into who did it or why because that is for the police to sort out, but suffice it to say Germany has a powderkeg on its hands right now and I think the politicians know it.