Esmond Bradley-Martin, one of the world's top ivory investigators, has been killed in Nairobi.
The 75-year-old, who has been crucial to the fight against the illegal trade in ivory and rhino horn, was found in his home with a stab wound to the neck on Sunday.
The former UN special envoy for rhino conservation, who had recently returned from a research trip to Burma, was found dead by his wife in their house in Langata.
He, his wife Chryssee Martin and colleagues were in the midst of discovering ivory and rhino markets, the traffickers and the modern-day uses.
Police, who are investigating the death, suspect it was a botched robbery.
Mr Bradley-Martin had authored several ground-breaking reports on rhino and ivory smuggling in Kenya as well as the trade in China, Vietnam, and Laos.
Nairobi DCI chief Ireri Kamwende told local paper The Star that they are yet to identify the attackers.
Shocking & sad news: Esmond Bradley Martin, investigator into the illegal trade in elephant ivory & rhino horn, found murdered in his home in Nairobi. Our thoughts are with his wife Chryssee https://t.co/YzfRAIkWcb pic.twitter.com/BeYYsFzVfd— Save the Rhino (@savetherhino) February 5, 2018
"We have already questioned a gardener and a cook who are employed at the home," he said.
The geographer had recently published a study into the declining ivory trade in China.
"With the end of the legal ivory trade in China, the survival chances for elephants have distinctly improved. We must give credit to China for doing the right thing by closing the ivory trade," he told The Star last year.
He had first come to Africa in the 1970s after a huge slaughter of elephants in the region.
Mr Bradley-Martin explained the purpose of his work to Nomad Magazine last year: "In Kenya, there were around 20,000 rhinos in 1970, but by the 1990s, most of the rhinos had been eliminated. The puzzle was: why were all these rhinos being killed, and where was the horn going?"
I'm devastated - Esmond Bradley Martin murdered in kenya yesterday - such a good, gentle, honest, brave man and Lulu and I were with him just a few days ago.. A man who has been fighting the ivory/rhino horn trade for years - yes I am devastated.— Robin Page (@skylarkwarrior) February 5, 2018
Elephant expert and CEO of Wildlife Direct Dr. Paula Kahumbu tweeted: "It is with deep shock & horror that we learn this morning of the death of long time conservationist, Esmond Bradley Martin, whom police say died in suspicious circumstances st his home in Karen, Nairobi. Esmond led investigations into ivory & rhino horn trafficking.
"Esmond was at the forefront of exposing the scale of ivory markets in USA, Congo, Nigeria, Angola, China, Hong Kong, Vietnam, Laos and recently Myanmar. He always collaborated with Save the Elephants and worked with many of us generously sharing his findings & views.
"Esmond was a global authority on ivory and rhino horn trafficking. We send our deepest condolences to his wife. RIP Esmond, pachyderms have lost a great champion."