Thousands rallied in Istanbul for jailed mayor Ekrem Imamoglu.
Imamoglu criticized a 'corrupt mindset' in a pre-written message.
The protest highlights ongoing political tensions in Turkey.
Strategic angle: One year after his arrest, supporters gather to protest against corruption charges.
Thousands rallied in Istanbul for jailed mayor Ekrem Imamoglu.
Imamoglu criticized a 'corrupt mindset' in a pre-written message.
The protest highlights ongoing political tensions in Turkey.