EX-DEA AGENT: Trump's border wall would 'serve no purpose' in the war on drugs

Retired DEA agent and "Deal" author Mike Vigil spent roughly 20 years undercover in Mexico and Colombia. Vigil argues that GOP presidential frontrunner Donald Trump's proposal to build a wall on the Mexican border will not stop drug cartels from sending drugs into the United States. Produced by Eames Yates Follow BI Video: On Twitter