On September 11, 2009, El-Masri was arrested after attacking Gerold Noerenberg, the mayor of Neu-Ulm. Shortly before the attack El-Masri tried to meet Noerenberg, but was prevented from entering the office and sent off by the police. He then took three of his six children with him, stormed the office and struck Noerenberg repeatedly in the face and threw a chair after him. He was arrested two hours after the attack in Senden. He confessed the attack, but kept silent about the motives at the time. Writing from his cell, he complained about the increasing licensing of brothels by the city, one of which he said desecrated a Muslim prayer room. He was sentenced to two years' imprisonment on 30 March 2010. His lawyer, Manfred Gnjidic, explained that El-Masri believed he was pursued by the secret services, trying to break or recruit him, and he intended to file an appeal.