I was in Tijuana nearly three years ago, and I spent time with people that were doing missionary work to help out the people down there. The stories I heard were crazy. Simply put, both corruption within the police force and sexual abuse is rampant. I have not looked deeply into this story, but nothing about it surprises me and is very plausible. Lives of foreigners or children were not really worth much.
To give an example of some of the craziness that happens, you can review this web site:
BreakingChains.org. (WARNING: some of his descriptions of what happens are graphic and disgusting. I don't want to hunt through the site to find specific ones to share. It is too disturbing, and I am not in the mood for that right now.) I met the guy that runs this web site. He breaks children out of forced prostitution. In all honesty, I am surprised that he is still alive. From what I recall, you can buy a child slave for something like $200 or rent them for a day for $20. If you give the child to the authorities, they get put in a state orphanage which is often just a front for a prostitution ring.