It was found in hundreds of cases—and the knowledge was invariably suppressed—that an alien suspect’s sudden and mysterious shifts and changes, his suspicious and watchful conduct, his evasive acts, all had to do with nothing more than the fact that the man had a mistress or so in another part of the city. The woman in his case very often was not the woman in the case at all, for there was no case, so far as the League was concerned. But countless men were quietly warned. Often with tears they implored the secrecy which was given them. There are hundreds, perhaps thousands, of men in America whose private lives are known to the League and not known in their own families. There is yet to be known the first case where any advantage ever was taken of the unintended victim caught in the general meshes of the Web; but it may be interesting for any of those of guilty conscience who by chance may read these lines, to know that their lives are filed away, cross-indexed, for future reference in the vast archives of the Department of Justice at Washington!
The extent of these “woman cases,” as they were known, is very considerable, and the per cent of suspect spy cases which simmered down to a petticoat basis is a very large one. A great part of the work of the League was done in finding the woman, if not in searching for her specifically. The League brought up from the deep-sea soundings of its steel meshes all the sordid and unworthy phases of human life on the part of both men and women. But while combing out the discards of human intrigue, the League often found the evidence it really sought. This was without fail used mercilessly and coldly.
One case, handled by the Central Division in Chicago, we may call the Otero case. Word came from El Paso that a certain prominent Mexican, a revolutionary and political leader with aspirations for a very high office in that republic, had come into the United States and was headed north, probably for Chicago. Nothing was known about him and his purpose excepting that his name was given. The League at once began making inquiries about Senor Otero. It was found that he was traveling in a special car. Obviously, therefore, he was a man of money. Ergo, he would go to a good hotel, and he probably would make a reservation in advance. Inquiries were made by telephone at all the leading hotels in Chicago, which in practically all cases were members of the American Protective League. Senor Otero was found to have reserved a large suite at the Blackstone, and had made the time of his arrival known. From that time on, he was in the hands of the American Protective League, although he never knew it. The boy who took his bag at the door was an A. P. L. operative, the bellhop who responded to his summons was an A. P. L. operative, his waiter at table was A. P. L., his night taxicab driver was A. P. L. In fact, the A. P. L. put Senor Otero to bed and woke him up in the morning, followed his activities during the day and knew what he was doing all night. It was not discovered that he was engaged in any plot against the peace of the United States, but was apparently active in the more pleasant task of spending some money he had gotten hold of in Mexico. If relatives or friends of the Senor Otero would be pleased to know how he spent it, the nature of his associations in Chicago by day—or night—and if they can persuade the Department of Justice to advise them, they can find the entire record of his stay in Chicago. Had he been engaged in any suspicious acts against this country, his return to Mexico might not have been so peaceful.
If an A. P. L. man knew the chemistry of any synthetic or invisible ink, he would not make the secret public any more than would M. I. D. Many devices for making and using these inks, however, are very generally known, although it is believed that Great Britain and France have gone farthest in classifying and developing them. A piece of a necktie has been taken from one German, a corner of which, snipped off and put in a glass of water, would make an invisible ink. A shoestring has been known to do the same thing, a small piece of it making enough for a letter or more. A shirt-stud has been described by a foreign operative, which, when unscrewed and dropped into a glass of water, would do the same thing and leave no trace. With what chemicals were these articles treated in order to make the ink? Ah, that is another matter. If the author knew, he could not tell. One thing is sure, it is not likely that the most inventive writer of “detective” stories could imagine anything more ingenious or more baffling than some of these well-known methods in use by our own men.
Mr. Byron R. Newton, collector at the port of New York, gave out a curious story on the work done by the Customs Intelligence Bureau, created as a lookout for smugglers and others. This service was employed in searching ships, examining baggage, looking out for explosive bombs, invisible writing, and so forth. Mr. Newton’s story appeared in the New York Herald of July 14, 1918, and from it one incident may be taken.
Through the Boarding Officials, a passenger who arrived the other day has furnished interesting material for the Intelligence Bureau investigators. The passenger, who for some time had been a resident of Germany, although an American citizen, said he had been approached in Dresden by German agents and asked if on his return to the United States he would obtain military and other information of interest to the Imperial German Intelligence Bureau. He was furnished with a code to be used by him for forwarding information to Germany and also with a formula for manufacturing an invisible ink, and with paper to be treated by a special process for correspondence. The passenger, in evidence of what he stated, offered four collars to the customs officials. They appeared to be ordinary negligee collars of cream-colored material—double, turn-over collars, medium height, such as many men wear with sport shirts or for informal occasions. The passenger explained the purpose of these collars as follows:
“I take a soup plate and I put boiling water in it and let it stand for about a quarter of an hour, after which I throw away the water. The plate being warm, I place one of these collars in it. I pour over the collar one hundred grams of boiling water and let it stand for half an hour. Then I wring out the collar, and the water that remains is my invisible ink. They call it ‘pyrogram.’ It looks like water, it is not poisonous and it can be drunk.
“I wash my hands, since they are wet with this ink, and take the paper and fold it crosswise and begin the letter, writing two fingers from the edge. I let it dry, and then take a glass of water and put about one teaspoonful of ammonia in it. With a piece of wadding dipped in this solution of ammonia and water, I rub the paper both ways, and thus prepare it on both sides. After this I place the paper in this wet condition between blotting paper and under heavy books or a trunk for three hours. You will not be able to recognize the paper any more. It looks like foreign writing paper, very thin and glazed. I can write anything I choose on this letter now. When they get the letter and develop it the writing appears positively black. I head the letter ‘Dear Bob’ and they know it is a code letter. When I am through with the letter I use the word ‘Schluss,’ because in developing it, they want to know if they have the entire letter, and that word ends it up.”
This passenger also told the examining officials that in carrying addresses without an address book, the German agents usually take a bone button of an overcoat or a large button of some sort and on the reverse side scratch the address with a diamond, sometimes also scratching instructions which they cannot carry in their heads. After this they treat the button with shellac, or, as they call it in Germany, “spitituslak.” That fills the crevices and dries rapidly. On reaching the destination, they use pure alcohol to wash off the shellac. They also write addresses on this paper and work them into leather buttons.
Cipher and code are part of the education of certain intelligence officers, but into a discussion of these matters we may not go, as they are secrets of the American Government. Our own experts were able to decipher and decode all the secret messages bearing on the great German plots in this country, but this was not usually A. P. L. work. Of course, the lay reader, or more especially the A. P. L. member, may know that a cipher means the substitution of some symbol, or some number, or another letter, for each letter of the alphabet. Or the real letters may be transposed, one to stand for another, in such a way that only the sender and receiver may understand. That looks hard to read? Not at all. It is easier than code. It is said that any cipher message can be unriddled in time.