Shirk said the Mexican military could easily stop the protests but might further galvanize public opinion against Pena Nieto's government.
Q&A: Protests over gas costs disrupt Mexico border crossings →
"We don't know exactly what she knows," said Shirk. "It may just be an interesting factoid in the war on drugs or it could be a vital clue for law enforcement."
Daughter of Mexican drug lord held in San Diego →