Mexican cartels 'major supplier' of synthetic drugs causing overdose deaths in U.S., GAO warns

Mexican transnational criminal organizations (TCOs) continue to drive the nation’s deadly synthetic drug crisis by sourcing, manufacturing, distributing and financially processing drugs such as fentanyl and methamphetamine, which have contributed to rising overdose deaths nationwide, a U.S. Government Accountability Office (GAO) report warned.

The 67-page analysis is mandated by the Preventing the Financing of Illegal Synthetic Drugs Act.

According to the Centers for Disease Control and Prevention (CDC), provisional data show that more than 42,000 overdose deaths involved illicit synthetic opioids in the U.S. in a recent 12-month period. Fentanyl, specifically, remains more potent than many other opioids, which increases the risk of fatal overdoses.

Mexican TCOs -- more commonly known as cartels -- are identified in the report as the major suppliers of the top two synthetic drugs driving overdose fatalities in the U.S.

“Mexican TCOs use diverse business strategies to directly or indirectly source fentanyl and methamphetamine precursor chemicals, primarily from China-based chemical companies,” read the report.

“According to DEA’s 2024 drug threat assessment and a nonprofit entity report, TCOs may obtain precursor chemicals through several channels: (1) directly from suppliers in China; (2) through intermediaries in the U.S., such as reshipping companies or complicit companies or individuals; and (3) via brokers who work independently of any TCO,” it added.

GAO noted that the DEA has reported that Mexican TCOs are “generally not directly involved in local sale and distribution” but they “leverage relationships with U.S.-based trafficking organizations who supply the drugs to local independent drug trafficking groups and gangs.”

These criminal organizations use a mix of electronic transfers and virtual currencies to fund purchases of precursor chemicals primarily from suppliers located in China.

GAO reported that the Mexican TCOs manufacture drugs in clandestine laboratories in Mexico before smuggling them into the U.S. for distribution. 

“TCOs move these drugs through Mexico and across the southwest U.S. border using tractor trailers, human mules, couriers, privately-owned vehicles, among other methods,” read the report. “Some traffickers pay other criminal organizations to access ports of entry, tunnels, or other smuggling routes.”

The TCOs also “maintain large distribution hubs across the U.S. to supply fentanyl and methamphetamine to regional cartel-affiliated traffickers in key cities such as Los Angeles, Phoenix, Houston, Chicago, Atlanta, and Miami,” the GAO report read.

The drugs are sold in various ways, including e-commerce platforms, online marketplaces, mobile apps, and social media.

The watchdog report found that the Mexican TCOs use money laundering techniques to hide proceeds from their illegal drug sales, such as bulk cash smuggling, funnel accounts, trade-based laundering, cryptocurrency exchanges, and the use of decentralized Chinese money-laundering networks that bypass traditional banks.

The GAO also warned that Mexican TCOs have “adapted to chemical restrictions by producing fentanyl and methamphetamine using less restricted chemicals.”

The report said that under policies put in place in January 2025 after President Trump took office, authorities are trying to disrupt cartel operations more aggressively. 

For example, Executive Order 14159 directs the Departments of Justice and Homeland Security to establish Homeland Security Task Forces in all 50 states.  Federal agencies said that it is still too early to fully assess the impact of these policy changes, the report said.

The report urges continued coordination and enhanced efforts across federal agencies to counter both the illegal trafficking of synthetic drugs and the complex financial systems used to launder their profits.