Esmond Bradley Martin: The daring investigator who took on the ivory poachers

Esmond Bradley Martin, one of the world's leading investigators into the global illegal ivory and rhino horn trade, has been found stabbed to death in the Kenyan capital, Nairobi. He worked undercover in some of the world's most dangerous and difficult places, photographing and documenting ivory markets, talking to traffickers and calculating black market prices to guide global conservation policy