Christian Ngoy Kenga Kenga was pronounced guilty of murder, desertion and the misappropriation of weapons and ammunition, the court said on Wednesday.

Jacques Migabo, another police officer, was sentenced to 12 years, while Paul Mwilambwe who had been a key witness in the trial was acquitted, UN-sponsored Radio Okapi says.

In 2011, four policeman were sentenced to death for the murder - but it was thought that there were other more high-ranking officials behind the killing.

DR Congo has not carried out the death penalty for many years.

Chebeya led the Congolese charity The Voice of the Voiceless, and was a critic of the government. He had received regular threats to his life during his career of more than 20 years.

His body was found tied up in the back of his car on a roadside in the capital, Kinshasa, in June 2010. The discovery came on the day that he had gone to police general headquarters to meet the then head of national police, Gen John Numbi.

His driver Fidèle Bazana went missing on the same day and later the authorities pronounced him dead.