Examining this piece of paper carefully, Mr. Pinkerton saw that it had been torn from a money-draft, and at once thought of the package in the express messenger's safe. Now it is a remarkable fact that no human power can tear two pieces of paper in exactly the same way; the ragged fibers will only fit perfectly when the two original parts are brought together. There remained no doubt, when this test was made in the present case, that the piece of paper found on conductor Danforth's east-bound train had been torn from the draft in the express-car robbed the night before on the west-bound train. The edges fitted, the red lines corresponded, and unquestionably some one had carried that piece of paper from the one train to the other. In other words, some one connected with the crime of the previous night had ridden back to Chicago twenty-four hours later with conductor Danforth. Mr. Pinkerton at once ordered a search made for the missing valise, and also an inquiry regarding the passengers who had ridden on conductor Danforth's train between Davenport and Chicago on the night following the murder. The valise was found on the ash-heap where the conductor had thrown it, and in the course of the next few days the detectives had located or accounted for all passengers on conductor Danforth's train, with the exception of one man who had ridden on a free pass. The conductor could only recall this man's features vaguely; and, while some of the passengers remembered him well enough, there was no clue to his name or identity. As it appeared that no other of the passengers could have been connected with the crime, efforts were redoubled to discover the holder of this pass. II So great was the public interest in the crime and the mystery surrounding it that three separate, well-organized investigations of it were undertaken. The Rock Island Railroad officials, with their detectives, conducted one; a Chicago newspaper, the "Daily News," with its detectives, another; and the Pinkertons, in the interest of the United States Express Company, a third. Mr. Pinkerton, as we have seen, concluded that the crime had been committed by railway men. The railway officials were naturally disinclined to believe ill of their employees, and an incident occurred about this time which turned the investigation in an entirely new direction and made them the more disposed to discredit Mr. Pinkerton's theory. This was the receipt of a letter from a convict in the Michigan City penitentiary, named Plunkett, who wrote the Rock Island Railroad officials, saying that he could furnish them with important information.