Two United Nations contractors, who had been kidnapped in the Democratic Republic of Congo, were found dead, the government said on Tuesday. Their translator was also found dead, NPR reported. American Michael Sharp and Swedish national Zaida Catalan had gone missing on March 12. Government spokesperson Lambert Mende said Catalan’s body had been decapitated, AFP reported.

The two were members of a group of experts that had been appointed by the United Nations Security Council. They had gone missing in the Kasai Central province. Villagers had found the bodies of one Congolese and two Caucasians not far from where they had disappeared. Catalan and Sharp had gone to Kasai Central earlier this month to investigate clashes between the Congolese Army and rebel groups, The New York Times reported. Catalan was said to have been responsible for investigating child soldiers.

UN Secretary General Antonio Guterres confirmed that the remains of the two investigators had been found and said the organisation will investigate their murders.

“Michael and Zaida lost their lives seeking to understand the causes of conflict and insecurity in the DRC in order to help bring peace to the country and its people,” Guterres said.

The UN has deployed around 19,000 as part of its peace-keeping force in DRC, which is its biggest and most expensive mission to date. Some parts of the country, notably in the east, has been hit by violence for decades as rebel groups have been fighting government forces.