Remember, the gripe being expressed here is that “left alone” is the action being described. You’re claiming that it’s hard to include all the same details without including that phrase, so let’s really re-write it with the exact same details so you can see how simple it is to just change the action:

A baby was found alone after days in a Phoenix, Arizona, apartment and was rescued by police officers last month after the infants mother had died, officials said Friday.