I abandoned the idea of following their trail in this immediate locality, so calling my men together, I told them that we would ride out for about five miles and make a complete circuit about the place, and in this way we would certainly find the trail on which they had moved out.  While making the circuit we discovered the tracks of twelve animals—­four mules and eight horses—­in the edge of some sand-hills, and from this point we had no trouble in trailing them down the Arkansas river, which they had crossed at Sand Creek, and then had gone up the latter stream, in the direction of Denver, to which place they were undoubtedly bound.  When nearing Denver their trail became so obscure that we at last lost it; but by inquiring of the settlers along the road which they had taken, we occasionally heard of them.

When within four miles of Denver—­this was on a Thursday—­we learned that the horse-thieves had passed there two days before.  I came to the conclusion they would attempt to dispose of the animals in Denver, and being aware that Saturday was the great auction day there, I thought it best to remain where we were at a hotel, and not go into the city until that day.  It certainly would not have been advisable for me to have gone into Denver meantime—­because I was well-known there, and if the thieves had learned of my presence in the city they would at once have suspected my business.

Early Saturday morning, we rode into town and stabled our horses at the Elephant Corral.  I secured a room from Ed. Chase, overlooking the corral, and then took up my post of observation.  I did not have long to wait, for a man, whom I readily recognized as one of our old packers, rode into the corral mounted upon Lieutenant Forbush’s racing mule, and leading another government mule, which I also identified.  It had been recently branded, and over the “U.S.” was a plain “D.B.”  I waited for the man’s companion to put in an appearance, but he did not come, and my conclusion was that he was secreted outside of the city with the rest of the animals.

Presently the black mule belonging to Forbush was put up at auction.  Now, thought I, is the time to do my work.  So, walking through the crowd, who were bidding for the mule, I approached the man who had offered him for sale.  He recognized me and endeavored to escape, but I seized him by the shoulder, saying:  “I guess, my friend, that you’ll have to go with me.  If you make any resistance, I’ll shoot you on the spot.”  He was armed with a pair of pistols, which I took away from him.  Then informing the auctioneer that I was a United States detective, and showing him—­as well as an inquisitive officer—­my commission as such, I told him to stop the sale, as the mule was stolen property, and that I had arrested the thief, whose name was Williams.