(CBS News) The debate in Washington about funding President Trump's border wall comes amid growing questions about a barrier's effectiveness in the fight against drug trafficking. Since 1990, Border Patrol agents have discovered at least 230 cross-border tunnels running from Mexico into California and Arizona, where they've seized loads of cocaine, methamphetamines and marijuana inside them.
Border Patrol agents not only have to protect what's above the border but also what lies beneath with smugglers taking advantage of existing infrastructure.
"This is already in place built by the cities to drain water," explained Kevin Hecht from inside a storm drain. He's the deputy patrol agent in charge in Nogales.
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