Nairobi - A world-renowned ivory investigator whose detailed reports contributed to the fight against elephant poaching and the illegal wildlife trade, was killed at his home in Kenya, police said on Monday.
Esmond Bradley Martin, a 76-year-old American geographer who had lived in Kenya for decades, died after being stabbed in the neck at his house in the Nairobi suburb of Langata on Sunday afternoon, police said.
"We have four suspects in custody," Nairobi Police Chief Japheth Koome said.
They were arrested on Monday afteroon, Koome said. He did not give further details as to their identities or suspected role.
Martin focussed on the demand end of the illegal rhino and ivory supply chain, describing, quantifying and analysing the Asian markets in China, Hong Kong, Vietnam, Laos and elsewhere.
His groundbreaking investigations, often co-authored with researcher Lucy Vigne, are credited with contributing to China's decision to close its legal ivory markets last year, said Paula Kahumbu, a leading Kenyan elephant expert and chief executive of Wildlife Direct, a conservation group.
"He was one of the most important people at the forefront of exposing the ivory trade, addressing the traffickers and dealers themselves," Kahumbu said.
Iain Douglas-Hamilton of Save the Elephants, a conservation and research organisation that funded and published Martin's reports over many years, described him, as "one of conservation's great unsung heroes."
"His meticulous work into ivory and rhino horn markets was conducted often in some of the world's most remote and dangerous places and against intensely busy schedules that would have exhausted a man half his age," Douglas-Hamilton said.
Martin was working on a new report into Myanmar's emerging role in the illegal wildlife trade when he was killed. It is unclear whether his murder was related to his work or simply criminal.
"He was my friend for 45 years and his loss is a terrible blow both personally and professionally," said Douglas-Hamilton.
Poaching has killed an estimated 110 000 elephants over the last decade, with transnational organised crime syndicates taking over the illicit trade.
The most recent figures, for 2016, showed the global trade in illegal ivory continues to thrive in light of record seizures despite a decline in poaching.