>> i was watching it. >> officer rodriguez is an expert on gangs and loves being an expert on gangs. he's fascinated with the political structure, fascinated with how gangs are changing. he's tough but fair. talks to the gang members in a very respectful way. >> can't stay in population. ever been part of a gang before this? >> helps them figure out what is the best way for them to make it through the system and make it through the system safely. >> let get you back in your cell. >> [ bleep ] upstairs. >> dozens of identified gang in the bexar county jail, two most dominant and dangerous are the texas mexican mafia and the tango blast, once family, but now enemies the texas mexican mafia started in early '80s and they began very small prison gang, as time went on, the