Tzi-kal-tza -- son of Billy Clark?

....Among the Nez Percé who died in exile was an old man named Halahtookit, or Daytime Smoke. According to Joseph's people, he was the half Indian son of William Clark, the American explorer the Nez Perce had sheltered more than 70 years earlier, the man who had first promised that the United States would always be their friend.