Perhaps half of police dog cases in the last twenty years involve canine sniffs, often of vehicles pulled over for traffic violations. The officer becomes suspicious and calls in a canine unit to see if the dog will alert to drugs (occasionally explosives). Before World War II, however, police dog cases most often involved tracking. Some cases are worth reading for the pictures of America that they give. Consider the following description of a crime from a 1926 case in Mississippi.
"Two police officers, Parnell and Danner, and several constables had repaired to a point about two miles southwardly from the city of Meridian, where they had information that whisky had been thrown from a train before, and would be on that night thrown from train No. 2, going northwardly, toward Meridian. So arranging themselves in two groups, the two police officers, Parnell and Danner, being together, they stationed themselves on the right of way 40 or 50 feet from the railroad track, to await the coming of the train about 11 o'clock on the night of the 20th of June, 1924; that when the train passed, they saw a negro named Hezekiah Clay throw three kegs of whisky off of the front vestibule of the negro coach, and immediately after the train had passed, which was running about 20 or 25 miles an hour, the defendant appeared upon the scene, passing on to where one keg of whisky was, which was farther away from them; that the defendant took up the keg of whisky and carried it away on his shoulder, and was gone seven or eight minutes; that the two officers then moved down in close proximity to the second keg, and when the defendant came back he came toward where the second keg had landed, and stopped. The officers, thinking he had discovered them, arose, flashed their flashlights upon him, and ordered him to throw up his hands and consider himself under arrest. To this order of the officers the negro responded by firing several shots at the officers. Officer Danner claimed that he was shooting at him (Danner). The officers responded to the negro's shots with a volley, each of them discharging his gun. No one was wounded. The negro ran off toward the mountains."
Bloodhounds were placed on the trail.
"The bloodhounds trailed toward the mountains in the direction which the officers said their assailant had gone, and finally, at 4 o'clock in the morning, they trailed to the home of defendant's mother, about a block and a half from Thelma Walker's house, where the defendant says he was living with Thelma Walker in concubinage."
The defendant, Boatwright, provided witnesses that gave him an alibi, and sought a continuance to produce more, which was not granted. The kegs of whisky were introduced in evidence, but do not seem to have connected the defendant with the crime, though viewing them may have incensed the jury. The only evidence connecting Boatwright to the crime appears to have been that the dogs tracked to a house where he was living. Was there racism here? Probably. It was well settled by this time in cases that considered tracking evidence that bloodhound testimony alone was not sufficient to convict. It could only be corroborative. It may be that the appellate opinion failed to review some uncontested evidence, but anything particularly probative would likely have been mentioned since it would have provided additional support for the decision to affirm. Boatwright v. State, 143 Miss. 676, 109 So. 710 (Sup. Ct. 1926).