The Supreme Court in the Democratic Republic of Congo prepared Friday for a new hearing into the 2010 murder by police of the country's most prominent human rights activist, Floribert Chebeya.

The highest judicial body was set to consider a request from civil parties close to Chebeya and the association he founded, La Voix des sans Voix (VSV -- Voice of the Voiceless), aiming to ensure that any final verdict in the ongoing murder trial cannot be overruled, in the wake of prior legal problems.

A military court in Kinshasa in 2011 convicted the deputy chief of police special services, Colonel Daniel Mukalay, of murder and sentenced him to death, together with three other officers. A fifth policeman was jailed for life, but three of the convicted men are on the run.

The case goes back to June 1, 2010, when Chebeya was summoned by then chief of national police General John Numbi, who later denied setting up any meeting. But he was suspended from his duties over the affair, which rocked the highest circles of power.

The next day, the rights activist was found dead on the back seat of his car, with his wrists showing signs of having been handcuffed, while his driver, Fidele Bazana, vanished and was presumed also murdered.

The condemned policemen turned to a military court of appeal and were again put on trial in June 2012, but those proceedings were suspended in May last year when civil parties in the affair denounced irregularities. Chebeya's relatives and VSV argue that the trial was flawed from the outset.

Prime suspect

The human rights organisation and others close to Chebeya, who had in his final years been an increasingly outspoken critic of President Joseph Kabila, in power since 2001, want ex-police chief Numbi to be prosecuted when the murder trial resumes.

They consider him to be the prime suspect in the deaths of both Chebeya and Bazana, but Numbi told the first military tribunal that he had never met the founder of VSV nor summoned him to a meeting at police headquarters.

Rostin Maketa, deputy director of VSV, said that Numbi's name came up "right from the first day of the disappearance and the discovery of Chebeya's body".

"We want him to be arrested and turned into a suspect," Maketa said. The suspended police chief was formally dismissed last December.

One defendant in the appeal suit, who fled to Senegal and took refuge there, directly implicated Numbi in the murder of the two men, but the court disallowed his evidence.

Whatever the Supreme Court decides in Friday's hearing, the appeal by lawyers for the five convicted police officers is due to resume in coming weeks.

Chebeya's death caused a diplomatic rumpus in 2012 when French President Francois Hollande publicly honoured his memory at the biennial Francophonie summit of France and mostly French-speaking African nations, held that year in Kinshasa.

Abdoul Aziz Thioye, deputy director of the United Nations office for human rights in the DRC, told AFP that "the general feeling is that justice has not been done" and that "the real culprits have not yet been punished".

"With the resumption of the trial ... this time we have high hopes that justice will finally be handed down," said Ida Sawyer, who works in Kinshasa for the New-York based organisation Human Rights Watch.

On Tuesday, Senegal's judiciary agreed to open an investigation into one of the convicted policeman, Paul Mwilambwe, who fled to the west African country. The authorities upheld a lawsuit filed in June by the International Federation for Human Rights (FIDH) on behalf of the victims' families.