FRANKFURT, July 21 (JTA) — German novelist Gunter Grass has accused prosecutors in the northern German city of Lubeck of deliberately obstructing their investigation of a recent series of right-wing extremist attacks. Several weeks ago, the walls of Grass’s Lubeck office were smeared with swastikas. But Grass later said that police did not develop pictures they took of the attack on his office for more than a week. In addition, Grass claimed that the investigating prosecutor showed no serious intent to investigate the crime, which the prosecutor called a “stupid boyish prank.” Three churches in Lubeck have recently been the targets of arson attacks. The attacks appear to be in retaliation for the policies of several pastors who had offered church asylum to refugees threatened with deportation. Grass, the author of “The Tin Drum” and other works, criticized the German government’s strict immigration policies, calling the arson attacks a sign of a “devilish interplay between government policies and right-wing youths.” Government officials rejected Grass’ claim. Lubeck has been previously in the headlines because of incidents that police suspect were carried out by right-wing extremists. In 1994 and 1995, the local synagogue was firebombed. Thousands of city residents turned out for spontaneous demonstrations after those attacks to protest right-wing extremism.