Machado was released after a brief detention while leaving a protest in Caracas Thursday on the eve of President Nicolas Maduro’s inauguration.

Maria Corina Machado, a 57-year-old engineer with rock-star appeal, became the fearless figurehead of Venezuela's opposition after being barred from challenging strongman Nicolas Maduro in elections last July.

Machado’s appearance at the rally was her first public appearance in months, since a government crackdown on Venezeulan opposition figures and their supporters last year.