No attention had been paid to this letter, although two certificates of stock accompanied it which had undoubtedly been in the bank's vault. Three other letters of a similar nature had been received later. To one of these the bank people had sent a guarded reply, which had called forth the following response, dated New York, October 20, 1876: "GENTLEMEN: Since you have seen fit to recognize the receipt of our letter, we will now send you our price for the return of the goods. The United States coupon bonds and money taken cannot be returned; but everything else--bonds, letters, and papers, to the smallest document--will be returned for one hundred and fifty thousand dollars. If these figures suit you, we will make arrangements, according to our promise, and you may have the goods as soon as preliminaries can be arranged for the safe conduct of the business. If you agree to this price, insert in the New York 'Herald' personal column the simple word 'Agatha.' "Respectfully, etc., "RUFUS." The special value of these letters was in helping the detectives to decide which one of several gangs of bank robbers then operating in the country was most likely to have committed the crime. Being familiar with the methods of each gang, Robert Pinkerton was able to draw useful inferences from evidence that would otherwise have been insignificant. He knew, for instance, that the notorious gang headed by James Dunlap would be more apt than any other to thus negotiate for the return of all the securities in a lump, since it was Dunlap's invariable rule to insist upon personally controlling the proceeds of his robberies until final disposition was made of them. On the other hand, the gangs headed respectively by the notorious "Jimmy" Hope, "Worcester Sam," and George Bliss might have divided the securities among the members, and then tried to negotiate a compromise on the individual portions. A fact of much significance to the Pinkertons was the rather remarkable interest in the case, and apparent familiarity with it, shown by one J. G. Evans, an expert in safes and vaults and the representative of one of the largest safe-manufactories in the country.