He grew up with Osiel Cárdenas Guillén and since 2003, he has headed the Gulf cartel, the second most powerful cartel in the country. Stealthy, Eduardo Costilla, El Coss, overcame internal divisions and now runs a fierce war in Tamaulipas and Nuevo León against their former allies, Los Zetas, who do not forgive him for his alliance to the Sinaloa cartel.
The PGR and the SSP claim that the capo has a presence in over 15 states and the United States, the DEA, including the Department of the Treasury consider him a threat to the security of the US.
Since late 1996 when Osiel Cardenas Guillen took over as head of the Gulf cartel, Eduardo Costilla Sanchez had a definite place in the structure of this criminal organization. Known as El Coss, he became the man most trusted to Cardenas Guillen and was known as "Mata Amigos" or "Killer of Friends" for his tendency to betray.
Although El Coss did not seem to own his own light, after the arrest of Osiel Cardenas in of March 2003, he positioned himself as the strongman of the second most powerful drug cartel in the country, the first one is led by Joaquin "El Chapo" Guzman. Currently his dominance extends to more than 15 states in Mexico, according to information from the Attorney General of the Republic (PGR) and the Ministry of Public Security (SSP).
In the United States, the Drug Enforcement Administration (DEA) classifies him as the drug dealer who has caused greater instability in the US, to the point that for over eight years the Treasury Department has consider him a threat to the security.
In 2002, the Federal Court of the Southern District of Texas, in the Brownsville Division, issued an "arrest warrant" against Costilla Sanchez. The charges: drug trafficking, threats, assaults and murders of U.S. federal agents and money laundering.
The Federal Bureau of Investigation (FBI) considers him "extremely dangerous" and has offered a reward of $5 million for information leading to his arrest.
Similarly, in March 2009 the PGR said that there is a reward of 30 million pesos for those who provide information on his whereabouts.