reporter: for centuries, legendary medicine men, the kallawaya, lived close to lake titicaca. ey were the doctors of the incan kings, often called witches of the andes. what remains of this culture today? we met aurelio ortiz, who calls himself one of the last kallawaya. aurelio: we kallawaya know the medicinal properties of roots, flowers, leaves, and fruits. i received my extensive knowledge about plants from my grandparents. look at this moss. you can cure many people who have been put in psychiatric wards with it. in traditional western medicine, you just call these people crazy. reporter: aurelio also has remedies for alzheimer's and cancer, but he won't tell us exactly which ones. a patient from the capital city of la paz has arrived at his practice. aurelio welcomes the young man between stuffed cats, tinctures, herbs, and roots. yasmani arze requested a ritual with coca leaves. yasmani: i want to know from aurelio what i need to do to live a healthier life. and i need advice for my life, my emotional world, and the future of my work. reporter: based on the shape of the