Just a small tip for any PIs... If your subject updates their Instagram story on a regular basis and you would like to view/download their updates anonymously, this can be done using the site 'StorySaver.net'.
There are actually many different websites which allow you to view Instagram stories anonymously, but the one I've linked is my personal favourite.
I have found that many subjects will regularly check to see who views their stories, some people check this obsessively. These sites are therefore essential if you need to keep tabs on people without them finding out.