NEW : This was a Mexican operation , the DEA says . The agents were allowed to leave after a standoff . Comment: Costilla is said to be the leader of the Gulf Cartel . Multimillion-dollar rewards were offered for his capture in Mexico and the United States .
NEW : This was a Mexican operation , the DEA says . Comment: Costilla is said to be the leader of the Gulf Cartel . Multimillion-dollar rewards were offered for his capture in Mexico and the United States .