  Recently, falsified images have been found in papers involved in research
misconducts. However, although there have been many image forgery detection
methods, none of them was designed for molecular-biological experiment images.
In this paper, we proposed a fast blind inquiry method, named FBI$_{GEL}$, for
integrity of images obtained from two common sorts of molecular experiments,
i.e., western blot (WB) and polymerase chain reaction (PCR). Based on an
optimized pseudo-background capable of highlighting local residues, FBI$_{GEL}$
can reveal traceable vestiges suggesting inappropriate local modifications on
WB/PCR images. Additionally, because the optimized pseudo-background is derived
according to a closed-form solution, FBI$_{GEL}$ is computationally efficient
and thus suitable for large scale inquiry tasks for WB/PCR image integrity. We
applied FBI$_{GEL}$ on several papers questioned by the public on
\textbf{PUBPEER}, and our results show that figures of those papers indeed
contain doubtful unnatural patterns.
