Bureau 13: For the d20 System

from the introduction

Bureau 13 is a roleplaying game where the characters are normal people who have survived supernatural events and attacks, and are later trained by the U.S. Government to secretly protect America and its interests from those threats. Once you are found as acceptable candidates for Bureau training (i.e. surviving that alien abduction intact and relatively sane), you are transported to a place where you stay for a year, and return at the end of the day of which you left!

user summary

This is essentially a "modification" of the the Bureau 13 RPG rules for use with the d20 System.