Mexicans vote in a presidential election dominated by two women -- a historic first in a country with a history of gender-based violence and discrimination. Thousands of troops are expected to be deployed to protect voters, following a particularly bloody electoral process that has seen more than two dozen aspiring local politicians murdered. "How is it possible that now even candidates don't want to stand because of this huge mafia who control everything we do?", says one voter in the capital Mexico City. IMAGES AND SOUNDBITES