Parts of the Stern article (the rest isn't new) 

Stalking is punishable. In germany you can get up to 3 years in jail. Frequently famous people are being followed by people with a mix of fantasy and jealousy. Popstar Madonna, Tennis player Steffi Graf, Topmodel Claudia Schiffer or actor Jodie Foster already have had those experiences. One of the Beatles founders John Lennon died in 1980 by a bullet, that was fired at him by an obessed fan. The past champion of tennis Monica Seles of 1993 hit a physcological sick fan in hamburg and here college Steffi Graf got stabbed in the back with a nife. 

It won't get this far with Tokio Hotel. Jost writes, the police has advised the musicians to collect evidence against the stalkers. Bill, Tom and other members of the Kaulitz family have started with that a few weeks ago and have filmed and photographed the stalkers. The stalkers responded very agressive to that. "for one, the hit a photocamera out of the hands of a family member". 

Source: 
Stern