DR Congo's famed Virunga National Park said on Thursday that the head of an armed group had been arrested over a three-year killing spree that had left 19 wildlife rangers dead.
The park, one of richest areas of biodiversity in the world, is the home of the mountain gorilla and dozens of other rare or endangered species.
After a six-month inquiry, Virunga wardens early Tuesday arrested suspected militia chief Jackson Muhukambuto on the outskirts of the city of Butembo, park director Emmanuel De Merode told AFP.
"We believe that Jackson Muhukambuto is directly responsible for the death of 19 rangers over the last three years," in addition to civilians and members of the armed forces, he said.
He described Muhukambuto as the head of a large group called Mai-Mai Jackson.
It operates in nearly half of the vast park, mainly around Lake Edward, the smallest of the African Great Lakes, on the border with Uganda, he said.
The Kivu Security Tracker, a US-headquartered NGO that monitors violence in eastern Democratic Republic of Congo, said Muhukambuto was a former army commander and veteran of the unrest that has gripped the region for the past 25 years.
Experts said he had good connections within the army and among tradespeople in the Nande ethnic group, the largest in the area.
He had also collaborated with the army to fight a notorious Rwandan Hutu group, the Democratic Forces for the Liberation of Rwanda (FDLR).
Guarding the 7,769-square-kilometre (2,999-square-mile) reserve, the oldest in Africa, is a high-risk profession.
Twenty-one rangers have died in the past year in clashes with armed groups that roam the area, many of them a legacy of two regional wars.