I thought I would call attention to this:
Valiant Comics in 1990-1 published some issues containing Metroid titles, the first of which, The Coming of a Hero, featured Samus being a member of the GF Police Force early in her career, before leaving for an unknown reason to become a bounty hunter. This was before the release of Metroid II even - so this idea of Samus' backstory has, indeed, been around for a long time. I guess now we're actually going to find out what the reason she left the force was!
http://images2.wikia.nocookie.net/metroid/images/c/cc/Mt_hero1.jpg
http://images2.wikia.nocookie.net/metroid/images/5/5a/Mt_hero2.jpg








