Thus, from one city to another, and through every part of the country, any criminal may be "shadowed" to-day as Schwartz was "shadowed," one set of detectives relieving another every twenty-four hours, and the man's every word and action be carefully noted down and reported, without his having the faintest suspicion that he is under observation. The task of "shadowing" a person who is traversing city streets is intrusted to men especially skilled in the art (for art it is) of seeing without being seen. This is, indeed, one of the most difficult tasks a detective is called upon to perform, and the few who excel in it are given little else to do. Where a criminal like Schwartz, upon whose final capture much depends, is being followed, two, three, or even four "shadows" are employed simultaneously, one keeping in advance, one in the rear, and two on either side. The advantage of this is that one relieves the other by change of position, thus lessening the chance of discovery, while, of course, it is scarcely possible for several "shadows" to be thrown off the trail at once. An adroit criminal might outwit one "shadow," but he could scarcely outwit four. A "shadow," on coming into a new town with a subject, reveals himself to the "shadow" who is to relieve him by some prearranged signal, like a handkerchief held in the left hand. The result of the "shadowing" in Schwartz's case was conclusive. No sooner was the brakeman out of Chicago than he began spending money far in excess of his income. He bought fine furniture, expensive clothing, articles of jewelry, presents for his wife, and laid in an elaborate supply of rifles, shot-guns, revolvers, and all sorts of ammunition, including a quantity of cartridges. The "shadows" found that in almost every case he paid for his purchases with fifty-or one-hundred-dollar bills. As far as possible these bills were secured by the detectives from the persons to whom they had been paid, immediately after Schwartz's departure. It will be remembered that the money taken in the robbery consisted of fifty-and one-hundred-dollar bills. IV In addition to this, it was found, by the investigations of detectives at Philadelphia, that Schwartz was the son of a wealthy retired butcher there, a most respectable man, and that he had a wife and child in Philadelphia, whom he had entirely deserted. This gave an opportunity to take him into custody and still conceal from him that he was suspected of committing a higher crime. The Philadelphia wife and child were taken on to Chicago, and Schwartz was placed under arrest, charged with bigamy.