MS-13

Mara Salvatrucha &mdash; commonly abbreviated as MS-13 &mdash; was a transnational criminal gang operating in cities across the United States, including Los Angeles, California and Baltimore, Maryland.

Early history
MS-13 was originally founded on the streets of Los Angeles by immigrants from El Salvador. Originally limited to local activities, such as extortion rackets, the gang gained influence nationwide in part due to the efforts of one of its members, Mexican immigrant Jorge Marquez. One of the few people to ever leave the group and live, Marquez would later gain international notoriety as the anarchist Zapata, but continued to hire the gang for contracts.

Members of MS-13 were distinguished by the heavy tattoos most had all over their bodies.

Hit on Jack Bauer
CTU's Director of Field Operations, Christopher Henderson, became the subject of an Internal Affairs investigation regarding misappropriated funds. Because the case hinged on Jack Bauer's testimony, Henderson organized a complex plan to have him assassinated. While Jack was undercover inside the Federal Holding Facility, as part of a mission to capture Zapata, Henderson made a deal with MS-13 leader Smiley Lopez to have his soldiers inside the prison to murder Jack, in exchange for reduced or commuted sentences. (In truth, Henderson had no way of holding up his end of the bargain.)

The first two attempts, led by Oscar Cisneros, were unsuccessful: Jack managed to incapacitate the Salvatruchas, and later that night staged a prison break, escaping into the city with his cellmate Emil Ramirez in order to continue his mission.

Later that night, Henderson's accomplice, Peter Jiminez, tracked Teri Bauer to Jack's location after Jack called her for help, allowing Lopez to send another hit squad after him. Once again, however, Jack survived the drive-by shooting, leading a furious Henderson to call Lopez personally and demand that he finish the job.

Eventually, Jack learned about Zapata's past involvement with MS-13 and tracked down Lopez himself, saving him from an assassin sent by a rival Ukrainian gang. Jack made a deal with Lopez: his information on Zapata, in exchange for the crystal meth that the Ukrainians had stolen from MS-13. After a few hours, Jack managed to return with the drugs, only to be double-crossed by Lopez and Cisneros, who still planned to kill him as part of his deal with Henderson. Jack killed Cisneros, then tortured Lopez to get the address of Kyle Risdow, one of Zapata's most frequent associates.

An hour later, Peter Jiminez arrived at Lopez's home to assassinate him, ensuring that nobody would ever discover the deal between him and Henderson.