FLORIBERT CHEBEYA, the head of a local NGO called Voice of the Voiceless, was found dead in his car on the morning of June 2nd. The evening before, he had set out to meet a police chief, John Numbi, a close aide of President Joseph Kabila and one of the country's most powerful men. Police reports of the circumstances of Mr Chebeya's death painted a humiliating picture. He was, apparently, in the back seat with his flies undone, alongside two used condoms, two tablets missing from a packet of a Viagra-type stimulant, strands of women's hair and fake fingernails.

But many people doubt the police version. After he had received several death threats, Mr Chebeya, long a critic of arbitrary arrests and the brutal repression of political dissidents in Congo, had feared for his life in the months leading up to his death.

When UN-sponsored elections took place in 2006, the first in four decades, Congo seemed to have embraced democracy. The country was supposed to have left behind decades of corrupt dictatorship under President Mobutu Sese Seko and a war between 1998 and 2003 that left about 5m people dead.

But since Mr Kabila won the election in 2006 he has become increasingly authoritarian. Two years ago a report by a New York-based group, Human Rights Watch (HRW), charted abuses that extended to murder, with bodies dumped in the Congo river, as well as the torture of political opponents and the imprisonment of thousands more. “The international community has been turning a blind eye for years to attacks against human-rights defenders and journalists in Congo,” says HRW's Anneke Van Woudenberg.

That may now be harder to do. Within a day of Mr Chebeya's death, the UN secretary-general, Ban Ki-moon, offered to help any investigation in the country, where nearly 19,000 UN peacekeepers are stationed. Big donor countries such as Britain, France, Canada and the United States also expressed concern. An international human-rights group condemned Mr Chebeya's “cold-blooded murder” and called for a joint commission of inquiry.

The Congolese government has since arrested several policemen over Mr Chebeya's death and suspended Mr Numbi. One of those arrested is Colonel Daniel Mukalay, who was named in the HRW report for putting electric batons on victims' genitals, staging mock executions and extracting false confessions.

But Congo's government has so far refused outside help. Its attorney-general says the country will conduct its own “sovereign” investigation, though a Dutch offer to send in a team of four autopsy experts may yet be accepted. Mr Chebeya's family, colleagues and UN officials have not been allowed unimpeded access to his body.

As Congo nears the 50th anniversary of its independence from Belgium on June 30th, Mr Chebeya's murky death suggests that 2006 was a false dawn. With Mr Kabila facing a difficult election race next year, repression is unlikely to let up.