Updated

A United Nations board of inquiry says two U.N. experts were likely slain in March by militiamen from Congo's violence-torn Kasai region, but it said further investigation and judicial proceedings are needed to determine the identity and motive of the killers.

The board's executive summary, which was obtained Wednesday by The Associated Press, says that "there was a reasonable likelihood that the killings were committed after consultation with other local tribal actors."

Michael Sharp of the United States and Zaida Catalan, a dual national of Sweden and Chile, disappeared March 12. Their bodies were discovered in shallow graves 15 days later.

The board says there is "a reasonable likelihood" that the same militiamen were responsible for the deaths of a Congolese interpreter and three motorcycle drivers accompanying the U.N. experts.