IN an interview less than four months ago the environmentalist Esmond Bradley Martin spoke of the issues surrounding the poaching of rhino horn and the elephant ivory trade, an issue extremely close to his heart. He praised India and Nepal for its efforts in rhino conservation, and predicted: “We can turn rhino poaching around if people allocate the proper resources”.

However, Martin will now never see whether the trade can truly be turned around. Last week the charismatic 76-year-old – described in the New York Times as “a fixture in Kenya’s wildlife scene, an eccentric American with a mass of white hair”, – was murdered. His wife, Chryssee Martin, found his body at their home in a Nairobi suburb, a stab wound in his neck. Local police say nothing has so far indicated a connection between Martin’s work and his death, but concerns have been voiced that there may indeed be such a link.

Those who knew Martin, or worked with him, voiced their shock and revulsion. The Save the Elephant charity said it was “deeply saddened” by the death of a man who had been its long-term ally, a “passionate champion of wildlife and meticulous researcher”. Wildlife Works said he was a “warrior fighting for those without a voice”.

Paula Kahumbu, a Kenyan elephant expert, told CNN that Martin had been an “icon” in conservation: "He was one of the only people who was doing real investigative work on ivory horn trafficking and rhino horn trafficking. His work helped conservationists redirect their efforts.”

Iain Douglas-Hamilton, founder of Save the Elephants, said Martin was 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 …He was my friend for 45 years and his loss is a terrible blow both personally and professionally.”

Martin’s case recalls that of Dian Fossey, the celebrated US-born conservationist and primatologist, who made a lifelong study of mountain gorilla groups in Africa. She was murdered in December 1985, in Rwanda, just before her 54th birthday.

Fossey’s book, Gorillas in the Mist, was turned into a film, with Sigourney Weaver as Fossey. Martin’s distinguished career and tragic end might, in time, attract the interest of film-makers.

Jeffrey Gettleman, who knew Martin, wrote last week that he was a dapper figure, a frequent sight at cocktail parties in snug-fitting, three-piece suits with brightly-coloured hankies in his breast pocket. “His hair was long and unruly and perfectly white, sitting atop his head like a giant cotton ball. He threw himself lavish birthday parties with belly dancers – sometimes he appeared in a cape.”

Martin was born into a prosperous New York family in April 1941. He studied geography at university in Arizona and in Liverpool. As he told Nomad magazine last October, his career began when he and his wife were looking at the illegal rhino-horn trade in the Indian Ocean, and they co-wrote a book, Cargoes of the East.

He said: “Around that time, we discovered that most of the rhino horn from East Africa was going to Yemen. What had happened was in the 1970s there had been a huge slaughter of elephants in East Africa, followed in the 1980s by rhinos. 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?”

Martin also documented the destruction of ancient rhino carvings in China, and was appointed the UN Special Envoy for Rhino Conservation. He targeted that destruction in China by getting a UK film crew to document it. This led to a 20-minute film that was broadcast across the world.

“The Chinese eventually blocked it,” Martin said, “but by 1993 we stopped the destruction of antiques and the legal domestic trade came to an end. China started using substitute materials instead.”

Martin was fearless, and often found himself at the sharp end. His research, National Geographic reported, “was often dangerous, requiring him to go undercover and pose as a buyer of illicit ivory and rhino horn.”

He sometimes worked as a wildlife spy for months at a time, immersing himself in the criminal underworlds of West and Central Africa or trawling through the souks of Yemen and the back streets of Hanoi, Rangoon and Beijing. His meticulous research and derring-do earned comparisons with Indiana Jones.

Douglas-Hamilton added that Martin had “produced 10 crucial reports into legal and illegal ivory markets in Africa, South-east Asia, the US and Europe. He played a key role in revealing the price of ivory in China had fallen prior to the Chinese Government committing to close its legal domestic market, and was working on important research on Myanmar when he died.”

Daniel Stiles, a wildlife researcher in Kenya who knew Martin well, said he changed the way in which investigations were conducted into the wildlife trade. “He brought that whole quantitative element that helped get the public’s attention,” he said. Martin, he said, was one of “the most sincere, honest and dedicated people I ever knew. He was always more interested in producing facts than building up his own reputation.”