How did Michael die according to Dr. Ranta?

Dr. Ranta tells Ramotswe that he was working at the farm on a grant from the Ford Foundation. He talks about the people who were there and how the South African woman Carla shared a room with Michael and then had an affair with Ranta. They used to meet at night in one of the huts. Michael found them one night and ran off into the bus. He fell into a ditch and broke his neck. They buried him and said nothing, fearing no one would believe he had died accidentally.