In South America it's called burundanga. Natural product. Refined, it's scopolamine. Think zombie drug, because once the person has taken it, their highest desire is to please you. It's frequently used to facilitate robberies and kidnappings south of the border.
Keep the handler in with the kid, the kids shoots up everything. Tell the kid to shoot himself, he does it. Handler walks out. Easy. Nobody will do a toxscreen for that. Murder-suicide of the someone and their family because they're inconvenient? Not hard to do. Anyone who can import cocaine can import burundanga.