What's behind US claims about a growing nexus between Latin America and West African drug cartels?

DW looks into a massive meth lab bust in Nigeria, during which three Mexican nationals were detained, and speaks with Dr. Oluwole Ojewale, an organized crime expert with the Institute for Security Studies in Dakar, Senegal. 

"The criminals are diversifying their operation, and that cannot be disconnected from the growing demand of various illicit materials, contrabands and drugs that are being consumed within the continent," Dr. Ojewale says.