Death certificates were issued in 1900 and filed in the Indiana State Dept Health Vital Records office. Some counties had death records prior to 1900 and they are on file in those counties.
You should be able to order copies of their death certificates from the State Dept of health and Dept of health in any county. There is additional info about death records at www.ingenweb.org/inewton/ p. 2. Successful Searching!