`` An adoption document made in the Orphans Court Records in St. Louis , Missouri , states , ` On August 11 , 1813 , William Clark became the guardian of ` Tousant Charbonneau , a boy about ten years , and Lizette Charbonneau , a girl about one year old . '
According to Bonnie `` Spirit Wind-Walker '' Butterfield , historical documents say that Sacagawea died in 1812 of an unknown sickness : `` An adoption document made in the Orphans Court Records in St. Louis , Missouri states , ` On August 11 , 1813 , William Clark became the guardian of ` Tousant Charbonneau , a boy about ten years , and Lizette Charbonneau , a girl about one year old . '