Mexican security forces have arrested a senior lieutenant of captured drug kingpin Joaquin "El Chapo" Guzman, the longtime boss of the Sinaloa Cartel, the government said on Tuesday.The attorney general's office announced on Twitter news of the capture of Damaso Lopez, one of the top-ranking figures in the Sinaloa Cartel, and said more details would follow shortly.Mexican media said Lopez was captured in Mexico City. Lopez, who Mexican officials say played a key role in orchestrating Guzman's first escape from prison in 2001, was believed to be locked in a violent power struggle for control of the Sinaloa Cartel in northern Mexico with El Chapo's sons.Guzman, who escaped twice from prison in Mexico, was recaptured for the last time in January 2016. One of the world's most wanted drug kingpins, he was extradited to the United States to face multiple charges on January 19, the eve of Donald Trump's inauguration as US president.