There are a very large number of persons who go into the detective business for the same reason that others enter the ministry—­they can’t make a living at anything else, Provided he has squint eyes and a dark complexion, almost anybody feels that he is qualified to unravel the tangled threads of crime.  The first resource of the superannuated or discharged police detective is to start an agency.  Of course, he may be first class in spite of these disqualifications, but the presumption in the first instance is that he is no longer alert or effective, and in the second that in one way or another he is not honest.  Agencies recruited from deposed and other ex-policemen usually have all the faults of the police without any of their virtues.  There are many small agencies which do reliable work, and there are a number of private detectives in all the big cities who work single-handed and achieve excellent results.  However, if he expects to accomplish anything by hiring detectives, the layman or lawyer must first make sure of his agency or his man.

One other feature of the detective business should not be overlooked.  In addition to charging for services not actually rendered and expenses not actually incurred, there is in many cases a strong temptation to betray the interests of the employer.  A private detective may, and usually does, become possessed of information even more valuable to the person who is being watched than to the person to whom he owes his allegiance.  Unreliable rascals constantly sell out to the other side and play both ends against the middle.  In this they resemble some of the famous diplomatic agents of history.  And police detectives employed to run down criminals and protect society have been known instead to act as stalls for bank burglars and (for a consideration) to assist them to dispose of their booty and protect them from arrest and capture.  It has repeatedly happened that reliable private detectives have discovered that the police employed upon the same case have in reality been tipping off the criminals as to what was being done and coaching them as to their conduct.  Of course the natural jealousy existing between official and unofficial agents of the law leads to many unfounded accusations of this character, but, on the other hand, the fact that much of the most effective police work is done by employing professional criminals to secure information and act as stool-pigeons often results in a definite understanding that the latter shall be themselves protected in the quiet enjoyment of their labors.  The relations of the regular police to crime, however, and the general subject of police graft have little place in a chapter of this character.