Despite failing health and warnings from his doctors, he set forth on what was to prove to be his last ethnographic survey in 1945 and was killed on 10 December, among the Tukúna people, by the Solimões river, near São Paulo de Olivença, Amazonas state..
Trots sviktande hälsa och varningar från sina läkare, påbörjade han det som skulle bli hans sista fältarbete 1945 och dog den 10 december bland Tukúna folket, vid Solimões floden, nära São Paulo de Olivença, Amazonas.