When he had arrested the same poacher for the tenth time inside the Kahuzi-Biega National Park, chief ranger John Kahekwa, exasperated, asked the man why he kept doing it.
"It's simple," the poacher said. "There aren't any jobs." "If you had a job would you stay out of the park?" asked Mr Kahekwa. "Yes," the poacher said. "I would."
That was the start of an extraordinary one-man effort to bring about what is probably the only hope of saving Africa's magnificent wildlife in the face of terrible human poverty: community-based conservation.
Forget fences, and notices saying "Keep Out". In Africa, when human need is paramount, they don't work. Giving people a stake in their local biodiversity, or satisfying their basic wants in such a way that they no longer impinge on protected wildlife, is now seen by many conservationists from the developed countries as the essential step in preserving the "charismatic mega-fauna", from lions to elephants, that is one of Africa's greatest gifts to the world.
African conservationists see this also, and none more clearly than Mr Kahekwa from the Democratic Republic of Congo (DRC), one of the continent's most remarkable environmental activists. His career, moving from wildlife policeman to social activist, mirrors precisely the shift in thinking in the last 20 years about how best to preserve the riches of the natural world in African nations blighted by extreme human need.
Kahuzi-Biega, his home range, is one of the world's greatest national parks. This quite colossal area of prime mountain forest on the eastern side of the DRC, 600,000 hectares of it, has been recognised as a Unesco World Heritage Site since 1980. More significantly, since 1997 it has been listed as a World Heritage Site In Danger.
Kahuzi-Biega was created for the astonishing variety of wildlife in its forests, from elephants to Ruwenzori otter shrews. But the undoubted stars are the gorillas: the eastern lowland gorillas, which, originally, roamed the mountain slopes in their hundreds.
Mr Kahekwa was fascinated by them, and by their environment, from boyhood. He grew up in the village of Miti, five miles from the park entrance, and he was the nephew of the Belgian game warden who was the prime mover in founding the park in the 1970s, Adrien Deschryver.
In 1983, at the age of 20, he joined the park staff as a gorilla tracker; it was his job to "habituate" gorilla family groups to the presence of humans, so that tourists could visit them. He did it with such success that eventually he could put names to the faces of no fewer than 155 animals.
As his skills grew, however, and he rose to become chief ranger, so did the difficulties he faced, especially from encroachment into the park by people living around its perimeter, who would set traps for game in which gorillas and many other animals were not infrequently injured or killed.
The poaching reached a climax in November 1993 when the park's and the Congo's most famous gorilla was killed. He was the silverback, or adult male, Maheshe, known throughout the country because he appeared on the Congolese 5,000-franc banknote. His death was greeted as an immensely depressing sign that the national park was simply not working as a wildlife reserve. By then, however, Mr Kahekwa had already had the conversation with the 10-times-a-loser poacher, and had decided to alter his approach.
In 1992, using his savings of $6,000, he set up his own charity, the Pole-Pole Foundation, devoted to bringing the interests of Kahuzi-Biega and those of the local community together (Pole-Pole means, slowly-slowly, or "gently does it", in Swahili).
He started with jobs: he persuaded the 47 worst poachers in the area to retrain as woodcarvers, and persuaded a Japanese donor to fund the planting of 10,000 young trees to provide the wood.
You can now buy stunning carvings of eastern lowland gorillas, done by men who were once killing them. Then he moved on to the poachers' wives "I knew they were poaching too," he says with a wry smile and provided them with jobs and income by buying a series of sewing machines, and teaching them to make shirts.
Pole-Pole broadened still further, helping to build schoolrooms so that environmental education could be carried out, and moving into tree planting on a large scale, as wood, for cooking and building, is one of the biggest demands for which the forest has been raided in the past: more than 300,000 young trees have now been provided for local communities, reducing timber demand substantially.
A principal supporter of Pole-Pole is the Gorilla Organization, one of the three charities featuring in this year's Independent Christmas Appeal. It sees Mr Kahekwa as embodying precisely the community-based conservation principles it endorses itself. Furthermore, he now does it in a war zone: in the unstable situation of the eastern DRC, rebels and insurgents pass through the park and conservation has become a dangerous business.
Mr Kahekwa's focus, however, remains unchanged. "I love Kahuzi-Biega, and I love my community," he says. "The park belongs to the community, and I want them to work together, so that they can both flourish and I think it can be done."