DRESDEN - A memorial in Germany for an Egyptian woman who was murdered inside a German court last year has been vandalised for the second time just weeks after being unveiled, police in the eastern city of Dresden were quoted by a German newspaper as saying. Marwa El-Sherbiny, the mother of a three-year-old and pregnant with her second child, was stabbed 18 times last July by a man she was testifying against during an appeal hearing. Three of the knife-shaped columns that make up the memorial for the 31-year-old Egyptian woman were knocked over, Zeitung newspaper reported. "Investigations are under way to arrest those involved in such vandalisation," a German official said. The organisers of the memorial, Buerger Courage, put up 18 columns in Dresden to symbolise the number of stab wounds. The July 1, 2009 courtroom killing sparked anger in several Islamic countries, where some accused Germany of tolerating xenophobia and anti-Islamic views. The German killer, a man of Russian origin, was convicted and given a life sentence. Germany has the second-largest Muslim population in Western Europe after France. Some groups in Germany said after the murder Islamophobia was rife, and criticised the German government for taking several days to condemn the murder.