Complex sentence: Many Bélmez residents believe that the faces were not made by human hands, and led some investigators to conjecture that it is a thoughtographic phenomenon unconsciously produced by the owner of the house, María Gómez Cámara.
Split into simpler sentences: Many Bélmez residents believe that the faces were not made by human hands. Some investigators to believe that it is a thoughtographic phenomenon unconsciously produced by the owner of the house, María Gómez Cámara.