One if by land

the long version

"President Chester Arthur calls semi-retired Murphy back to duty when, with a pending meeting of world leaders in New York City, prostitutes are being murdered and dismembered in the streets. Arthur's special assistant William Burke travels to New York with Murphy where Murphy is given authorization to take command of the investigation. So important is the meeting with world leaders to Arthur that he calls upon the services of the Pinkerton Detective Agency to assist Murphy. Murphy finds himself saddled with a diminutive Pinkerton's Detective named Melvin Knoop. From Scotland, he's rarely left the Pinkerton's office in Chicago, but he has a keen sense for forensics work and not much else. Weeks of investigation lead to a break in the case and although Murphy and Knoop come close, the killer escapes New York. The killer surfaces again in Fort Smith, Arkansas, and Murphy and Knoop begin the chase once again. From Fort Smith, Murphy and Knoop track the killer clear across the west until there is a final confrontation and the darkest of secrets is revealed."--