Currently it’s possible to search by either author or “first author” but there’s no way to restrict search to last author.
This would be useful because there’s a convention in writing scientific papers that the last author in a list of author names will be the senior author (or principle investigator). This means that someone may want to do separate searches for first author (the person who probably actually did the experiment) and last author (the person heading the lab or research group).
it would be useful to be able to do these searches when setting up smart groups or when searching the library from the tab pane.