KINSHASA, (Reuters) – Democratic Republic of Congo  will not allow international bodies to participate in an  investigation into the death of a leading human rights activist,  the country’s top legal adviser said.

Floribert Chebeya, head of Voice of the Voiceless, a local  NGO, was found dead on the outskirts of Kinshasa on June 2,  prompting the United Nations to offer assistance and the United  States, Canada, Britain, and France to express concern.

“We will not conduct a joint investigation — this is a  sovereign investigation,” Attorney General Flory Kabange Numbi  told Reuters in an interview.

A group of 55 NGOs, including Amnesty International and  Human Rights Watch, said over the weekend that an independent  probe into Chebeya’s death was crucial to ensuring the  investigation’s result is credible.

Congo authorities have arrested several police officers  since Chebeya’s death, and the country’s police chief was  suspended to help the investigation “take place smoothly”,  according to Interior Minister Adolphe Lumanu.

“Suspending the police chief is a step in the right  direction, but what is urgently needed is for the DRC government  to establish an independent commission of inquiry on what  happened and ensure that justice is done,” said Anneke Van  Woudenbourg of Human Rights Watch.

Kabange Numbi said in the interview that he wanted an  autopsy on Chebeya’s body he ordered last week to go ahead  despite a request from the family for an independent autopsy.

“If there are any objections after the results of the  autopsy, the family can ask for a second or third autopsy  afterwards,” he said.

The Dutch embassy in Congo had offered to send a team of  four experts to help with the autopsy. U.N. Secretary General  Ban Ki-moon had also offered the services of the U.N. mission  MONUC in a joint probe.