Mario Ruiz Massieu is the brother of assassinated Jose Francisco (Pepe) Ruiz Massieu, and a former Deputy Attorney General for Mexico (1993-1994). He led the investigation into his brother Pepe's murder, but gave it up after several months stating the investigation was being blocked by high-ranking PRI officials. He later was accused of trying to protect Raul Salinas.

On September 15, 1999, the former Mexican justice official apparently killed himself at his home in New Jersey rather than face money-laundering charges in the U.S. Ruiz Massieu had been under house arrest in the U.S. for several years as he fought U.S. attempts to extradite him to Mexico to face charges including money laundering and graft. A Houston jury had found that $8 million in his Texas bank accounts was paid him by drug cartels (in particular the Gulf Cartel) in exchange for protection. In his suicide note, Ruiz Massieu blamed Presdient Zedillo for his own death and that of his murdered brother.

• Proceso's
report (2/16/97) on the U.S.Justice Department's witness testimony in its lawsuit against Mario Ruiz Massieu. The witnesses implicate ex-president Carlos Salinas de Gortari, his siblings Adriana and Raul, his father Raul Salinas Lozano, and his ex-brother-in-law Jose Francisco Ruiz Massieu in drug trafficking operations. Includes documents/notes on witnesses testimony.