He's the Colombian narco who rose from humble origins to become the biggest wholesaler of cocaine in the world. 
Dairo Antonio Usuga, better known by his nickname, Otoniel, used torture and murder to rise to the top of the feared Gulf Clan Cartel, but he cut a different figure earlier this month when he pleaded guilty to drug trafficking in a New York court and agreed to hand over $216 million in reparations.
Niall Donald chats with Toby Muse, author of 'Kilo: Inside the Cocaine Cartels', about the demise of Otoniel and the impact it will have on the coke trade.

Crime World, with Nicola Tallant, is a weekly Iri…