In appearance and manner the professional criminal has not changed much in the last decade. I knew him first over ten years ago, when making my earliest studies of tramp life. I saw him again five years ago, while on a short trip in Hoboland, and we have met recently on the railroads; and he looks just about as he did when we first got acquainted.
Ordinarily he would not be noticed in mixed company by others than those accustomed to his ways. He is not like the tramp, whom practically any one can pick out in a crowd. He dresses well, can often carry himself like a gentleman, and generally has a snug sum of money in his pockets. It is his face, voice, and habits of companionship that mark him for what he is. Not that there is necessarily that in his countenance which Lombroso would have us believe signifies that he is a degenerate, congenitally deformed or insane, but rather that the life he leads gives him a look which the trained observer knows as "the mug of a crook." He can no more change this look after reaching manhood than can a genuinely honest man, who has never been in prison, acquire it. I had learned to know it, and had become practised in discovering it, long before I became a policeman. It took me years to reach the stage when in merely looking hurriedly at a criminal something instinctively pronounced him a thief, but such a time certainly comes to him who sojourns much in criminal environment. There are, of course, certain special features and wrinkles that one looks for, and that help in the general summing up, but after awhile these are not thought of in judging a man, at least not consciously, and the observer bases his opinion on instinctive feeling. Given the stylish clothes to which I have referred, a hard face, suspicious eyes which seem to take in everything, a loitering walk, a peculiar guttural cough, given by way of signal, and called the thief's cough, and a habit of lingering about places where a "sporty" constituency is usually to be found, and there is pretty conclusive evidence that a professional thief is in view. All of this evidence is not always at hand; sometimes there is only the cough to go by, but, the circumstances being suspicious, any one of them is sufficient to make an expert observer look quickly and prick up his ears.