John DeWitt is not explicitly listed in the 1852 Outhouse Company. However, it is extremely likely that he was amongst the 10 adults and 5 children that company records say made up the traveling party of Martin Potter. This conclusion was reached based on the following information: John and his sister Polly were living in the Potter household in Iowa at the time of the 1850 federal census. The DeWitt and Potter families were related. Martin Potter is documented in the 1852 Outhouse Company with 14 other individuals who are not named. John and his wife are seen in the 1860 census living close to the Potters in California, and part of their household in the 1870 census.
John is last seen in the 1870 census. Further research is needed to narrow the date of his death.