Thomas family

I am in search of death and/or burial information about my ggg grandfather, Zerah B. Thomas. He and wife, Nancy, and children lived in Champlain in the 1840's, as listed in the 1840 census. I assume he passed away sometime, then, before the 1850 census, as only Nancy, his sons Charles and Edwin, daughter Laura, and Charles' wife, Wealthy, are listed there. I subscribe to ancestry, my heritage and family search, and have found no information there. Any help in finding information will be much appreciated. His parents were John and Zadya Beach Thomas, who resided in the Chazy area.