Police in Istanbul have detained 47 people in dawn raids linked to a corruption investigation that saw the city’s mayor imprisoned last month. His arrest sparked Turkey’s largest protests in more than a decade. Among those arrested Saturday in Istanbul, the neighboring province of Tekirdag and the capital, Ankara, are senior officials from Istanbul Metropolitan Municipality, local media reports. The March 19 detention of Istanbul Mayor Ekrem Imamoglu, who is the main challenger to President Recep Tayyip Erdogan’s 22-year rule, saw hundreds of thousands of people flood the streets of Turkish cities to protest what many consider a politically motivated case. The government insists Turkey’s judicial system is independent.