A whole year passed before any promise of success came to cheer the express company and the patient detectives. In the summer of 1884, Robert Pinkerton, having received information that a professional burglar, who had been arrested some weeks previous for a burglary at Milwaukee, had valuable information about an express robbery, immediately journeyed from New York to Milwaukee to interview the man. He learned from the burglar that some years before he had operated with a man named John Donahue; that about the time of the Susquehanna robbery Donahue had been away from home, and that shortly after the robbery he had returned with plenty of money and paid off several old debts. Mr. Pinkerton at once recognized in Donahue a notorious thief who, to escape justice, had taken up his residence at Fort Erie, Canada, where he had opened a hotel.
The burglar also gave Mr. Pinkerton a description of a man who had visited Donahue at his hotel on several occasions, and who had the general appearance of a workman. He suspected that this man had been in some way concerned with Donahue in the Susquehanna robbery; he knew that he had resided at one time in Buffalo, New York, and worked in the shops there, and he thought that he might be then living in Susquehanna, Pennsylvania.
From the description, Mr. Pinkerton was able, on going to Susquehanna, to identify the suspected man with one George H. Proctor, who had formerly been foreman in the railroad company's shops, but had resigned his position some months before and moved to Buffalo. In the investigation that was at once begun it was found that Proctor had recently been speculating largely in oil and spending money freely, although while living in Susquehanna he was known to have had no resources besides his salary. It was learned further that Proctor had deposited money with three Buffalo banks and had accounts with various firms of brokers, and also that he was paying frequent visits to gambling-houses and in general leading a fast life. Proctor's deposits, it was learned, had at one time amounted to about eleven thousand dollars, but most of this sum had been subsequently drawn out and lost in speculation.
All of this was strong presumptive evidence against a man who was known to have been poor a few months before, and a more significant discovery was made a little later, when Proctor went on a trip to Canada, evidently on important business. The detective who followed him found that the men with whom he had dealings, and with whom he passed nearly the whole time of his visit, were professional thieves, well known to the police.
In view of all that had come to light, it was decided to effect Proctor's arrest. This was made easy by his habit of coming to Susquehanna every few weeks to see his wife and three children, who had remained there. During these visits it had been remarked that he was especially intimate with employees of the railroad and express companies who were connected with the ticket-office.
All unsuspicious of the danger that threatened him, Proctor took the train from Buffalo on the night of Saturday, November 16, with a ticket for Susquehanna. Word was at once telegraphed to Robert Pinkerton, who, in company with E. W. Mitchel, superintendent of the United States Express Company, started for Susquehanna, reaching there Monday morning. They learned that Proctor was still in town, but keeping very closely to his house. It was not until ten o'clock in the evening that he appeared on the street, his purpose in going out being to purchase some groceries. As he came from the store Robert Pinkerton stepped forth from his place of waiting and took him into custody. He was taken to a private house, where Mr. Pinkerton passed nearly the whole night in conversation with him. Before daylight Proctor had made what purported to be a full confession.
Proctor stated that he had moved to Susquehanna in 1880, having resided in Buffalo previous to that time. While in Buffalo he had occasionally of a Sunday visited Fort Erie, Canada, and there had made the acquaintance of John Donahue. At first he did not know that Donahue was anything more than the keeper of a hotel. He found him an entertaining companion, a good story-teller and singer of comic songs, and very generous with his money. They came to see much of each other, and after Proctor's removal to Susquehanna they kept up an occasional correspondence. Proctor, having a monthly pass over the Erie Railroad, and being able to procure passes on other roads, made several trips to Fort Erie, always stopping at Donahue's hotel. On one of these visits he chanced to read aloud to his friend the newspaper account of a clever robbery in Montreal, where a band of sneak-thieves had robbed a paymaster of a sum of money he had in a bag to pay off employees. This turned the conversation to criminal exploits, and Proctor related the circumstances of the express robbery at Susquehanna some years before. Donahue showed great interest, and inquired how it happened that the express company had so large a sum of money at Susquehanna. Proctor explained about the extensive railroad shops there, and incidentally remarked that the same system of paying the hands was still in practice. Donahue then requested Proctor to ascertain for him how much money was being shipped each month at that time, the day of shipment, the train, the kind of safe used on that train, and full details about the lock—whether opened by a combination or a key. Donahue professed that his only motive in seeking this information was curiosity, and Proctor promised to learn what he could.
It was about a fortnight after this that the two men met again, Proctor having secured all the facts about the monthly transfer of money from New York to Susquehanna. These he confided to Donahue, who seemed greatly pleased at the report. He showed Proctor the greatest attention, spending money freely. Then he pressed Proctor with further questions, asking how the money was wrapped up, what kind of pouch it was carried in, and so on. Finally he came out bluntly with the opinion that Proctor was a fool to waste his time working in a dirty shop when he might be living in luxury. Then, seeing that the foreman took no great umbrage at this suggestion, he asked him if he could get an impression of the safe-key, and also one of the key to the door of the ticket-office. After some show of reluctance, Proctor finally consented to try.
Returning to Susquehanna, Proctor took advantage of his friendship with employees about the ticket-office to get possession of the keys long enough to take the desired impressions, and these he mailed to Donahue, in whose service he was now fully enlisted. Donahue wrote back, expressing satisfaction, and saying that he and another man, named Collins, had paid a secret visit to Susquehanna, and had found everything as Proctor had represented. A little later Proctor went to Canada again, and was introduced to Collins. At this meeting it was arranged that Donahue should procure a canvas bag like the one used by the express company, and that a dummy money package should be placed inside, so that a substitution might be effected on the arrival of the next shipment. Proctor was to take no active part in the robbery, but was instructed to return home and continue at his work, showing no concern, whatever happened.
"If there's an earthquake at Susquehanna when pay-day comes around, you don't know anything about it, do you understand?" Such was the final order given to Proctor, and he obeyed it implicitly.