the scent
is still warm. Scores of men work on different aspects of the case. The
Finger-print Department may be trying to identify a thumb-print from
among their records; in another part of the building the photographers
have made a lantern slide of certain charred pieces of paper, and are
throwing a magnified reproduction on a screen for closer scrutiny; a
score of men are seeking for a cabman who might have driven the murderer
away.

It may be that these steps will go on for days and weeks with dogged
persistence. This stage of investigation has been aptly likened to a
jig-saw puzzle which may fall from chaos into a composite whole at any
moment. Once the hounds have glimpsed their quarry it is almost hopeless
for him to attempt to escape. His description, his photograph, specimens
of his writing are spread broadcast for the aid of the public in
identifying him wherever he may hide. Men watch the big railway
stations, out-going ships are kept under surveillance, for the C.I.D.
has two or three staff men resident in many parts. They are also
maintained at ports like Boulogne and Calais.

The co-operation of the provincial and foreign police is obtained, and
the wide publicity of newspapers. The whole-heartedness with which the
public throws itself into a hunt of this kind has disadvantages as well
as advantages. A score of times a day people will report someone "very
like" the wanted man as seen almost simultaneously in a score of
different places. All these reports have to be immediately investigated.

And with the search for the culprit the ceaseless search for evidence
goes on. It is no use to catch a murderer if you cannot adduce proof
against him. The enthusiasm of the investigators is not called forth by
a blood-hunt. It is all a part of the mechanism. The C.I.D. and its
members are merely putting through a piece of business quite
impersonally. "A murder has been committed," they say in effect. "We
have caught the person we believe responsible, and this is the evidence.
It does not matter to us what happens now. The jury are responsible."

It once fell to the lot of the writer to see an arrest for a murder with
which the world rang. The merest novice in stage management could have
obtained a better dramatic effect; the arrest of a drunken man by an
ordinary constable would have had more thrill. It was in a street
thronged with people passing homewards from the city. A single detective
waited on each pavemen