Margaret Warholm lived at Santa Maria Senior Citizens Home in Regina until October 2013.
Medical records show Warholm reported losing 30 pounds in a year and had compression fractures in her vertebrae.
She also had a large bedsore on her back that her family believes could have been prevented.
Ombudsman Mary McFadyen's investigation comes after the health minister requested she look at the case.
The Opposition has pointed to Warholm's situation as an example of why minimum care standards should be set in the province.
McFadyen's office says it has received other complaints regarding long-term care in Saskatchewan, and the ombudsman was already in the process of investigating these cases.
One of McFadyen's goals will be to determine if there are systemic problems affecting long-term care.