In presenting this work to the public the author has no apologies to make nor favors to ask. It is a simple history of his connection with the Police Department of Chicago, compiled from his own memoranda, the newspapers, and the official records. The matter herein contained differs from those records only in details, as many facts are given in the book which have never been made public. The author has no disposition to malign any one, and names are used only in cases in which the facts are supported by the archives of the Police Department and of the criminal court. In the conscientious discharge of his duties as an officer of the law, the author has in all cases studied the mode of legal procedure. His aim has been solely to protect society and the taxpayer, and to punish the guilty. The evidences of his sincerity accompany the book in the form of letters from the highest officers in the city government, from the mayor down to the precinct captain, and furnish overwhelming testimony as to his endeavors to serve the public faithfully and honestly. No effort has been made to bestow self-praise, and where this occurs, it is only a reproduction, perhaps in different language, of the comments indulged in by the newspapers of Chicago and other cities, whose reporters are among the brightest and most talented young men in all the walks and professions of life. To them the officer acknowledges his obligations in many instances. Often he has worked hand-in-hand with them. They have traveled with him in the dead hours of the night, in his efforts to suppress crime or track a criminal, and have often given him assistance in the way of suggestions.