"Boniface Matthew Maliango, commonly known as 'Shetani' or 'The Devil', is one of Tanzania's most notorious ivory traffickers. Today he was given a 12-year sentence," the PAMS Foundation, which finances the government's fight against poaching, wrote on its Facebook page.
The 47-year-old, considered the biggest ivory trafficker in east Africa, was arrested in Dar es Salaam in September 2015 after a year-long manhunt.
The Elephant Action League, which fights wildlife crime, said he was believed to be responsible for killing thousands of elephants at the head of 15 poaching syndicates operating throughout Tanzania, Burundi, Zambia, Mozambique and southern Kenya.
The hunt for Maliango and the Ivory Queen features in the 2016 Netflix documentary "The Ivory Game", on which Leonardo Di Caprio was an executive producer.
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According to the International Union for Conservation of Nature (IUCN) the number of African elephants has fallen by around 111,000 to 415,000 over the past decade.
The killing shows no sign of abating with around 30,000 elephants slaughtered for their ivory every year.
A recent census showed a 60 per cent drop in the country's elephant population between 2009 and 2014.