Sherlock Holmes had the case of the dog that didn’t bark, but it has taken two dozen apartment complexes and a testing company in Tennessee to bring the art of canine detection into the “CSI” age.

And the evidence is right underfoot.

Canine DNA is now being used to identify the culprits who fail to clean up after their pets, an offense that Deborah Violette, for one, is committed to eradicating at the apartment complex she manages.

Everyone who owns a dog in her complex, Timberwood Commons in Lebanon, N.H., must submit a sample of its DNA, taken by rubbing a cotton swab around inside the animal’s mouth.