It is then generally only a question of time before his whereabouts are ascertained.

Once he is "located" the same method is followed in securing additional evidence or material in the nature of a confession or admission tending to establish guilt.

Having previously "roped" the murderer's friends, the detective now proceeds to the more difficult task of "roping" the murderer himself.

Of course, the life of a detective in a Pennsylvania coal mine would be valueless if his identity were discovered, and yet the most daring pieces of detective work are constantly being performed under these and similar conditions.
Where the criminal is not known, the task becomes far more difficult and at times exceedingly dangerous.
One of my own friends, an Italian gentleman, spent several months in the different mines of this country, where Italians are largely employed, investigating conditions and ascertaining for the benefit of his government the extent to which anarchy was prevalent.

It was necessary for him to secure work as a miner at the lowest wages and to disguise himself in such a way that it would be impossible for anybody to detect his true character.