e been the result of his improper
and unofficial methods will never be known, but in all probability great
inconvenience would have been caused to a number of innocent persons and
the whole course of justice thwarted had it not been for the
intervention of the great and famous M. Lecoq.

M. Lecoq's interest in the bank robbery case was largely a personal one.
Even detectives have hearts, and M. Lecoq had loved with heart and soul
a charming young girl named Nina Gipsy. Under the name of Caldas in one
of his innumerable disguises, he had wooed her for many months. When he
thought at last that he had won her affections, she had fled to the
protection of no less a person than Prosper Bertomy himself. The cashier
cared nothing for her, but embittered by an estrangement that had sprung
up between Madeline and himself, he had sought forgetfulness in her
society. Bertomy's arrest gave Lecoq an opportunity for a noble revenge.
He determined to prove to the woman he loved his superiority over his
rival by saving the cashier from disgrace.

Though the case looked black against Bertomy, for it was shown that he
was heavily in debt, and living far beyond his means, Lecoq was
satisfied that he had not committed the crime. When Fanferlot,
hopelessly befogged, called for his advice at his house in the Rue
Montmartre, the great detective deigned to explain the preliminary data
and the deductions from the data he had made.

The scratch on the safe door, slight and minute as it was, was his
starting-point. How had it been made? He had found by experiment that it
was impossible to make such a scratch upon the varnish without the
exercise of considerable force. It was clear, therefore, that the
scratch by the keyhole could not have been made by the thief in his
trembling anxiety to get the business he had undertaken accomplished.
But why was such force used?

For a long time Lecoq puzzled over this problem. Then, with Fanferlot,
he tried an experiment. In his room was an iron box varnished like the
safe. Taking the key of this box from his pocket, he ordered Fanferlot
to seize his arm just as he put it near the lock. The key slipped,
pulled away from the lock, and sliding along the surface of the door,
left upon it a diagonal scratch, almost an exact reproduction of the one
on the safe.

From this simple experiment Lecoq deduced that two people were present
when the safe was robbed; one wanted to take the money, the other wanted
to p