KENTUCKY -  It's a place few civilians ever see but Spectrum News 1 was granted special access to a U.S. Customs & Border Patrol checkpoint where agents screen international packages entering the United States. 

“We are the last line of defense before those goods enter the US commerce," Thomas Mahn said. Mahn is with U.S. Homeland Sercurity.

His team is responsible for finding all the bad and potentially harmful things sent through the mail. Agents routinely find prohibited food and produce attempting to enter the country as well as illegal substances and harmful chemicals.

In fact, during this interview agents located and prevented nearly 60 pounds of a Fentanyl precursor from reaching its intended destination. The sole use of this chemical is to create the very deadly opioid.

“And that’s the danger that comes through and that’s why we have officers out there searching for this stuff every single day and every single night," Mahn said.