  The short-time behavior of quantum decay of an unstable state initially
located within an interaction region of finite range is investigated using a
resonant expansion of the survival amplitude. It is shown that in general the
short-time behavior of the survival probability $S(t)$ has a dependence on the
initial state and may behave either as $S(t)=1-\mathcal{O}(t^{3/2})$ or as
$S(t)=1-\mathcal{O}(t^{2})$. The above cases are illustrated by solvable
models. The experiment reported in Ref. [1] does not distinguish between the
above short-time behaviors.
