Who Is ‘Don Flaco’? José Ángel Rivera Zazueta and the U.S. Fentanyl-Chemical Case

What officials and news reports say about José Ángel Rivera Zazueta, known as “Don Flaco”. Everything below is attributed to its source. Accusations are allegations, not findings: anyone not convicted is presumed innocent.

Role, as officials describe it

• Treasury said his network operates on a global scale with nodes in the United States, Mexico, South and Central America, Europe, Asia, Africa, and Australia. [U.S. Department of the Treasury, 2023-01-30 · official record]
• Treasury said he imports precursor chemicals from China into Mexico, which are then used to manufacture synthetic drugs including fentanyl, MDMA (ecstasy), crystal methamphetamine, 2C-B, and ketamine. [U.S. Department of the Treasury, 2023-01-30 · official record]

Accusations and charges

• Treasury also said he is responsible for moving large quantities of cocaine from Colombia to the United States, Spain, Italy, Guatemala, Mexico, and other countries in Europe and Central America. [U.S. Department of the Treasury, 2023-01-30 · official record]
• Mexico's security secretary accused him of coordinating and financing an organization dedicated to transporting chemical precursors used for fentanyl production from China to Mexico and the United States. [Reuters, 2026-09-22 · news/research]

Sanctions and designations

• In January 2023, Treasury's Office of Foreign Assets Control designated him pursuant to Executive Order 14059 for procuring precursor chemicals to manufacture and traffic illicit fentanyl and other synthetic drugs to the United States. [U.S. Department of the Treasury, 2023-01-30 · official record]
• Treasury said he worked closely with the OFAC-designated Chinese chemical transportation company Shanghai Fast-Fine Chemicals, which shipped various, often falsely labeled, precursor chemicals to drug trafficking organizations in Mexico for illicit fentanyl production; OFAC had designated that company on December 15, 2021, also under E.O. 14059. [U.S. Department of the Treasury, 2023-01-30 · official record]
• The same January 2023 OFAC action also designated his associates Nelton Santiso Aguila of Mexico and Jason Antonio Yang Lopez of Guatemala for aiding the procurement and importation of fentanyl precursor chemicals into Mexico. [U.S. Department of the Treasury, 2023-01-30 · official record]
• In a September 29, 2026 action covering 21 individuals and 25 entities tied to the Sinaloa Cartel, Treasury again listed him and called him a "senior Sinaloa Cartel leader," saying former Chihuahua customs official Rafael Buenrostro Martín was his close friend and had provided political favors and influence to further his criminal enterprise, and that Diosvany Chapotín Villalba had worked with him to launder drug proceeds. [U.S. Department of the Treasury, 2026-09-29 · official record]
• Reuters' September 2026 arrest report says he was "sanctioned by the US State Department in January 2023," which conflicts with Treasury's own press release showing the designating authority was Treasury's OFAC, not the State Department. [Reuters, 2026-09-22 · news/research]

Names and aliases

• Mexican authorities and Reuters identify him as Jose Angel Rivera, also known by his alias Don Flaco; U.S. Treasury records give his full name as Jose Angel Rivera Zazueta. [Reuters, 2026-09-22 · news/research]

Key events

• He was arrested on September 22, 2026, in the Hipódromo neighborhood of the Cuauhtémoc borough in Mexico City, in a joint operation by the FGR's Criminal Investigation Agency and the SSPC using information shared with the FBI and the DEA. [Reuters, 2026-09-22 · news/research]
• On September 23, 2026, the DEA said its intelligence and information sharing had helped Mexican authorities arrest him, describing him as one of the DEA's highest-priority targets and an alleged coordinator and financier of chemical precursor trafficking from China to Mexico and the United States. [PorEsto!, 2026-09-23 · news/research]
• The U.S. ambassador to Mexico, Ronald Johnson, highlighted the bilateral cooperation behind the detention on September 23, 2026, writing on social media that when the two countries work together, there is nowhere to hide. [López-Dóriga Digital (via Lado.mx), 2026-09-23 · news/research]
• Mexican press accounts attributed to DEA reporting say he controlled precursor flows through Mexico City International Airport from at least 2020 and at one point lived in Taiwan coordinating shipments; these claims are untested in court. [DIME Noticias, 2026-09-29 · news/research]

Our coverage

• Who Is ‘El Mayito Flaco’? Anaheim-Born Ismael Zambada Sicairos, the Son of ‘El Mayo’ the U.S. Now Calls the ‘Undisputed Head’ of the Sinaloa Cartel’s Los Mayos Sep 30, 2026
• Mexico Blacklists Them Too: All 46 U.S.-Sanctioned ‘Mayito Flaco’ Targets — Including Baja Gov. Marina del Pilar’s Ex-Husband Carlos Torres — Added to Mexico’s Blocked-Persons List Sep 29, 2026
• Anaheim-Born ‘Mayito Flaco’ Among 21 Sanctioned: Treasury Says Los Mayos Hired Hitmen in Southern California and Bought Protection in Tijuana and Mexicali — Reaching the Baja Governor’s Ex-Husband Sep 29, 2026
• Arrested in Mexico City: ‘Don Flaco,’ Accused by U.S. of Running a China-to-Mexico Fentanyl Chemical Pipeline for the Sinaloa Cartel Sep 23, 2026

Sinaloa Cartel profile · More “Who is” profiles

Last reviewed: September 30, 2026. If you are named here and believe something is wrong, contact us via our corrections page.