Hi , Almost 12 years since your posting - re death in Southern Alberta
Because of current postings to the site - just curious if you were able to find the information you were seeking - or at least - had the names of you Grand aunt - given name - and maiden surname - could help as there may have been references made to her parents - or siblings - etc
Was it determined that the poisoning was a criminal offence - or perhaps - food that had gone bad ? - If you know the aprox place where the farm was - there may have been a news story -
perhaps Local Public library - would have some knowledge - Provincial Archive may be able to advise -
Glenbow Museum & Archive - may be a good source of information