BBC News
By Will Grant
image captionNezahualcóyotl is home to more than a million people
Flying over Nezahualcóyotl in a police helicopter gives a sense of the challenges its residents face.
Originally built on the drained bed of Lake Texcoco, the suburb stretches out below in a patchwork of low-income housing with more than a million people crammed inside.
Ciudad Neza, as it is commonly known, is now the most densely populated place in Mexico, part of the vast urban sprawl outside Mexico City.
image captionThe suburb stretches far into the surrounding hills
Over the years. criminal networks have taken hold, often with the complicity of local police.