  The role of controlled disorder in the strong correlated narrow gap
semiconductor candidate FeGa$_3$ has been investigated. Polycrystalline samples
were synthesized by the combination of arc-melting furnace and successive
annealing processes. Deviations of the occupation number of Fe and Ga sites
from those expected in the pristine compound were quantified with X-ray
analysis. Besides that, electrical transport and magnetization measurements
reveal that hierarchy in Fe and Ga site disorder tunes the ground state of
FeGa$_3$ from paramagnetic semiconducting to a magnetic metal. These findings
are discussed within the framework of Anderson metal-insulator transitions and
spin fluctuations.
