I have a spreadsheet with three rows - Last Name, Role, Institution.
There are approximately 500 columns with the applicable information,
with multiple variations of each. I would like to do the following
sorting:

I would like to alphabetically sort by last name all the people who
have to same role of "Investigator", without sorting any other
information. So at this point, I should have all the people who have
the role of "investigator" listed alphabetically at the the top of the
spreadsheet.

Now what I want to do is take all the people who weren't sorted and
place them in the applicable institution group based on the associated
investigator.

For example, let's say I have "Adams", as an "Investigator", at "ABC
Hospital". I would like to take all the people who are from "ABC
Hospital" and place them in the rows underneath "Adams". Then, we have
"Smith" as an "Investigator", at "123 Hospital". I want to take all the
people from "123 Hospital" and put them underneath "Smith", and so on.

So, in short, I want to sort by Investigator, then Last Name, then
Institution. All other people from the same Institution would then be
placed under the Investigator from that Institution.

Confusing, I know. Any help would be awesomely appreciated.