U.S. jury convicts Mexico's Gulf Cartel manager in drug case McAllen, Texas (Reuters) - A U.S. federal jury on Friday convicted a high-ranking member of Mexico's Gulf Cartel of conspiring to possess and import marijuana and cocaine to the United States, the latest blow to Mexican drug bosses in recent weeks. Juan Roberto Rincon-Rincon, a so-called plaza boss for the cartel, was convicted on all counts in the drug trafficking conspiracy case following a week-long trial in Brownsville, Texas, U.S. Attorney Kenneth Magidson said. Rincon-Rincon, 41, was accused of heading the cartel's operations in Rio Bravo, Tamaulipas, Mexico, a prime area for drug traffickers that borders the Rio Grande near McAllen, Texas. Prosecutors said that under Rincon-Rincon's leadership, the cartel netted more than $20 million from smuggling operations. Key testimony in the trial came from Rafael "El Junior" Cardenas-Vela, Jr., nephew of former Gulf Cartel leader Osiel Cardenas-Guillen, who is serving a 25-year sentence in a U.S. prison. Cardenas-Vela, a fellow cartel plaza boss, pleaded guilty to a drug conspiracy charge this year and awaits sentencing, Magidson said. Rincon-Rincon faces between 10 years and life in prison at a sentencing hearing set for January. Rincon-Rincon worked closely with Jorge Eduardo "El Coss" Costilla, who since 2003 allegedly headed the Gulf Cartel following Osiel Cardenas-Guillen's arrest. Mexican authorities arrested Costilla September 13 in Tamaulipas, the northeastern Mexico state where the cartel operates. Arrests and turf battles have weakened the Gulf Cartel since 2010, when it dissolved its alliance with the Zetas, which rose to power from a group of Mexican army deserters in the late 1990s. Mexican authorities said they struck a serious blow against the Zetas on Wednesday, when naval forces arrested Ivan "El Taliban" Velasquez in San Luis Potosi. Velasquez is listed by the Mexican government as one of the country's most-wanted drug kingpins. Also this month, Mexico arrested Mario Cardenas in Tamaulipas. He is accused of helping run the Gulf Cartel since his brother Antonio Cardenas, known as "Tony Tormenta," was killed in a 2010 gunfight with the Mexican government. They are brothers of Osiel Cardenas-Guillen. The recent takedowns of high-level Mexican drug cartel members come as the country's new president, Enrique Pena Nieto, is set to take office on December 1. About 60,000 people have been killed in drug-related violence since Mexican President Felipe Calderon took office in late 2006. Reporting by Jared Taylor; Editing by Mary Wisniewski and Xavier Briand