BERLIN, July 29 (JTA) Police here have bungled an investigation into the extremist music scene by inadvertently arresting an informant who was providing valuable information to police in the neighboring state of Brandenburg. Tilo S., 27, was arrested July 20 as his group, White Aryan Rebels, was about to give a concert for 100 neo-Nazis in Berlin, police said. The group is known for its 2001 CD, “Notes of Hate.” One of the songs on that CD, “This Bullet Is for You,” calls for the murder of German Jewish leader Michel Friedman and of the interracial children of tennis star Boris Becker, among others. Regional authorities in Brandenburg said Tilo was informing them about big players behind the extreme right-wing music business. They said their investigation was undermined by the arrest. But Berlin state authorities said they had officially proclaimed their intention to crack down on the music scene weeks ago, and would have expected their Brandenburg counterparts to let them know of any ongoing investigations. Plans reportedly are in the works for better coordination between police in these two neighboring states in former east Germany. Meanwhile, Tilo remains in jail. According to the daily newspaper Berliner Morgenpost, police found incriminating material, including skinhead music and flags with swastikas, during a search of his apartment. According to German officials, the popularity of music with racist, anti-Semitic and ultranationalist lyrics has increased in recent years. The music is downloaded from the Internet, particularly through U.S. providers, to avoid German laws against Nazi material.