Mr. Pollock reported that for several weeks previous to the robbery he had suspected that he was being followed. He also reported that on the day of the robbery he had been in the shop of the largest pawnbroker in Omaha, and that while he was there two noted Western gamblers had entered the shop and been presented to him as possible customers. He had made a trade of some diamonds with one of the men, and, in the course of the negotiations, had shown his entire stock. While the trade was in progress a negro on the premises had noticed, lounging about the front of the shop, a man in a slouch-hat who suggested the robber. From these circumstances it was decided that the robbery might be the work of an organized gang, who had been waiting their opportunity for many days, and had selected one of their number to do the actual deed. All his life it had been Mr. Pinkerton's business to study criminals and understand their natures. He knew that a crime like this one was much beyond the power of an ordinary criminal. Let a robber be ever so greedy of gold, reckless of human life, and indifferent to consequences, he would still think many times before declaring war to the death upon twelve men in a narrow car, on a swiftly moving train. This was surely no novice in crime, reasoned Mr. Pinkerton, but a man whose record would already show deeds of the greatest daring; a brave fellow, though a bad one. And even among the well-known experienced criminals there must be very few who were capable of this deed. Mr. Pinkerton, therefore, set himself to studying the bureau's records and rogues' gallery to first pick out these few. Page after page of photographs was turned over, drawer after drawer of records was searched through, and at last a dozen or more men were decided upon as sufficiently preeminent to merit consideration in connection with the present case. Photographs of these dozen or so were speedily struck off, and submitted by the detectives to all the men who had been in the smoking-car at the time of the robbery, to the conductor of the train and the trainmen, to other passengers, to farmers and others who might have seen the robber while making his escape, and to various people in Omaha. The result was startling. Conductor D. M. Ashmore, without hesitation, selected from the dozen or more portraits one as that of the robber. Mr. Shaw, the Omaha well-digger, who had sat just behind the robber, selected the same photograph, and was positive it pictured the man he had tried to talk to. Other passengers also picked out this photograph, as did various persons who had caught sight of the man as he escaped.