Channel 2 Investigates

Inside the smugglers' trail: How cartels overtook metro Atlanta streets

From Mexico straight to Georgia: How deadly drugs are flooding our streets

ATLANTA — Why is stopping drug cartels on the border so difficult and how are the dangerous drugs they bring into the country ending up in our neighborhoods?

In a four-part special investigation, Channel 2 Action News gave viewers a close-up look at the fight against fentanyl, a drug driving a wave of overdose deaths across metro Atlanta and the nation.

[READ MORE: Fentanyl overdose deaths tied to fake prescription pills, deputies say]

In Part 1, Channel 2 investigative reporter Mark Winne got a firsthand look at the smugglers' trail and spoke with officers who explained how drug cartels are carrying out the trafficking.

In Part 2, Channel 2's Tom Regan traveled to Arizona and met with a Drug Enforcement Administration agent, who outlined how drugs on the border make their way to Georgia.

In Part 3, Regan learned dangerous cartels aren't the only ones funneling deadly drugs into the country. Synthetic drugs cooked up in state-sanctioned chemistry labs in China are sold online and mailed through the U.S. postal service, unbeknownst to carriers.

In Part 4, DEA agents told Winne cartels based in Mexico now control the Georgia drug trade.