It's pretty well established that alchemists (and by extension investigators) do not have a caster level for things like Craft Wondrous Items, Magic Arms and Armor, etc. And since investigators don't get the caveat that alchemists do that lets them use their alchemist level as their effective caster level for Brew Potion, they would not be able to use Brew Potion either. (Although, in a home game with me as GM, I'm pretty sure I'd let Brew Potion happen. It seems reasonable. Just not RAW.)
No, I'm afraid that Investigators don't qualify for the craft magic item feats.
Edit: Ninja'd by a few seconds. :)