Former Mayor Clara Lopez (R) places a sash around Gustavo Petro (2nd R), after he was sworn in as Bogota's new mayor, at Bolivar Square in Bogota January 1, 2012. Petro was a former guerrilla of the M-19 group and senator of the republic with center-left policies. The mayorship of Bogota is considered the second highest political office in Colombia, after the President. REUTERS/John Vizcaino (COLOMBIA - Tags: POLITICS)