Transparency International Rwanda (TI-Rwanda) has said it is not entirely satisfied with a 20-year jail sentence handed by a court on Thursday to two former policemen found guilty of the murder of their staff.

Gustave Sharangabo Makonene, a researcher at TI-Rwanda, was murdered in 2013 after he reportedly uncovered a mineral smuggling ring stretching from the DR Congo into Rwanda, according to police investigations.

He had particularly discovered that two policemen were involved.

On Thursday, court in Western Province sentenced the two to 20 years in prison - a move the global anti graft body said "sends a message that there is no impunity for people who try to stop the fight against corruption.”

But the international watchdog said that it was disappointed that a maximum sentence was not handed to the killers.

"Although justice is done, we are not satisfied with it because this is a capital offence which deserves a maximum sentence, we shall consult with the members of the deceased’s family to see whether we can appeal,” said Marie Immaculée Ingabire, the chairperson TI Rwanda, in a statement released Friday .

Elena Panfilova, the vice chair of Transparency International, said the organization would not be intimidated by criminals in the fight against graft.

"Our message to the corrupt is clear: you will not get away with it. We are pleased to see these cold-blooded killers were found, tried and imprisoned, but it does nothing to end the deep sorrow we feel for the loss of Gustave,” she said.

"As this terrible story draws to an end, we must not forget one thing: Gustave was a hero and governments everywhere have an obligation to protect the brave people who work to uncover corruption and put themselves at risk for the good of others.”

But the Minister of Justice, Johnston Busingye, told Sunday Times yesterday that the aggrieved party was free to appeal. He said that he would be concerned if there was no appropriate justice system for those not satisfied with the court decision to appeal.

"They are free to have an opinion; and that is their right. The prosecution is there and the defense is there. Lack of that is what would concern me. If they [TI] feel it was unfair or a low sentence, they will appeal,” the minister said.

Last September, Police in Kigali arrested two of its officers - Corporals Nelson Iyakaremye and Isaac Ndabarinze in connection with the death of Makonene, on July 17, 2013.

Makonene, 33, joined Transparency International Rwanda in 2011 and worked as a coordinator of the Advocacy and Legal Advice Centre in Rubavu at the time of his death.

His body was found by residents on the shores of Lake Kivu in Nyamvumba Sector, Rubavu District.

Police said Makonene was a victim of a well orchestrated plot after he discovered that the suspects were aiding mineral smugglers to transit through Rwanda.