That was all there was to them, but it doesn't take an expert in plot building to think of a dozen stories that could lie back of that supposedly clandestine trip on the eighth of June.
Tyson didn't go into particulars at the time. He contented himself with turning the letters over to the department, with the request that the matter be looked into at once. Said that his wife had handed them to him and that he knew nothing more about the matter.
All that the postal authorities could do at the time was to instruct him to bring in any subsequent communications. But, as the letters stopped suddenly and Tyson absolutely refused to state whether he knew of anyone who might be interested in causing trouble between his wife and himself, there was nothing further to be done. Tracing a single letter, or even two of them, is like looking for a certain star on a clear night—you've got to know where to look before you have a chance of finding it—and the postmark on the letters wasn't of the least assistance.
Some three or four weeks later a similar case cropped up. This time it was a woman who brought in the letters—a woman who was red-eyed from lack of sleep and worry. Again the communications referred to a definite escapade, but still they made no open demand for money.
By the time the third case cropped up the postal authorities in Madison were appealing to Washington for assistance. Before Bolton and Clarke, the two inspectors originally assigned to the case, could reach the Wisconsin capital another set of the mysterious communications had been received and called to the attention of the department.
During the three months which followed no less than six complaints were filed, all of them alleging the receipt of veiled threats, and neither the local authorities nor the men from Washington could find a single nail on which to hang a theory. Finally affairs reached such a stage that the chief sent for Allison, who had already made something of a name for himself, and told him to get on the job.
"Better make the first train for Madison," were the directions which Elmer received. "So far as we can tell, this appears to be the scheme of some crazy woman, intent upon causing domestic disturbances, rather than a well-laid blackmailing plot. There's no report of any actual demand for money. Just threats or suggestions of revelations which would cause family dissension. I don't have to tell you that it's wise to keep the whole business away from the papers as long as you can. They'll get next to it some time, of course, but if we can keep it quiet until we've landed the author of the notes it'll be a whole lot better for the reputation of the department.
"Bolton and Clarke are in Madison now, but their reports are far from satisfactory, so you better do a little investigating of your own. You'll have full authority to handle the case any way that you see fit. All we ask is action—before somebody stirs up a real row about the inefficiency of the Service and all that rot."
Elmer smiled grimly, knowing the difficulties under which the department worked, difficulties which make it hard for any bureau to obtain the full facts in a case without being pestered by politicians and harried by local interests which are far from friendly. For this reason you seldom know that Uncle Sam is conducting an investigation until the whole thing is over and done with and the results are ready to be presented to the grand jury. Premature publicity has ruined many cases and prevented many a detective from landing the men he's after, which was the reason that Allison slipped into town on rubber heels, and his appearance at the office of the postmaster was the first indication that official had of his arrival.
"Mr. Gordon," said Allison, after they had completed the usual preliminaries connected with credentials and so forth, "I want to tackle this case just as if I were the first man who had been called in. I understand that comparatively little progress has been made—"