There is no definitive proof that Alexander was the son of Robert Marshall but the circulstantial case is strong.Robert's wife was Margaret McCandless, and Alexander's middle name was McCandless, so he was almost certainly their son.Alexander's name is spelled out completely on his land patent record, viewable/printable at http://www.glorecords.blm.gov/PatentSearch/Default.asphttp://www.glorecords.blm.gov/PatentSearch/Default.asp?
His records sometimes get mis-indexed because they used the abbreviation Mc. for his middle name; and indexers pick this up as McMarshall.The Barth. marriage record to Mary Ellenwood is like that.
An online source gives Alexander's date of death as 26 Jan. 1865 in Bartholomew Co., but I can't confirm that as I found no marked grave for him.He's probably at Mt. Healthy, or maybe Jonesville.No marker in either township, and I have as complete a record as there is for that area.I did find a marked grave for Mary Melinda Ellenwood's father, Adolphus Ellenwood, at Jonesville Cemetery, d. Sept. 4, 1858, 62Y 2M 2D.There's a good entry for these Ellenwoods on the LDS website, http://www.familysearch.org/Eng/Search/frameset_search.asphttp://www.familysearch.org/Eng/Search/frameset_search.asp
Ancestry.com has a long file on the Reesers, Alex's first wife; but not much on him, or their 3 children.Couldn't find them after 1860.By the time Alex died in 1865, those kids had neither natural parent living and both Marshall grandparents dead also.(You can access full records at Ancestry.com for free at most public libraries.)
Kate York does have a death record in Clay Co., Brazil City death records, book 7, p. 44.Presume you've gotten this death record--if you get a certificate, you want to be sure and ask for ALL the information provided.Clerks sometimes just fill in a few blanks on the modern form, and leave out details that only genealogy researchers are interested in.Are there newspaper obits available from that period? 1890s obits here are VERY few & thin unless it was for the important folks.
Mary Ellenwood married her first husband, James Griffith, in Jennings Co.I did find online full dates for him, 13 Mar. 1819-27 Mar. 1855, said to have died at Jonesville.No marked grave for him out there.Other Griffiths in Jennings Co. were Catholic, and Catholic churches kept good records.Any chance your family had Catholic ties?If so, go check out the local church parish records.