The specially-trained dog has sniffed out evidence in three Delta fires in the past five years -- a house blaze in Tuk that killed five and the Chief Julius fire in Fort McPherson, in which she helped lead to the conviction of two people. The Edmonton-based dog was in town again last week, where she sniffed out evidence that a substance such as gasoline was used to spread a Bonnetplume Road building fire. RCMP have launched an arson investigation.

"She's trained to sniff out any petroleum-based accelerant: gasoline, kerosene, anything like that," said Edmonton City Police Const. Odd Gunderson, the dog's handler.

"She searches through just like any police dog and when she finds a scent she'll sit down, or claw at it if it's a weak scent. She gets a treat when she finds the scent."

Patty started out life as a Philadelphia street dog before she came to the attention of the pound there, who noticed that they just couldn't catch her. Survival instincts being the most important quality among such working dogs, the pound called a nearby police-dog training school and said something along the lines of, "We think we have a recruit because we can't catch her."

Patty was finally taken into custody after a dragnet, and although the little dog with the amber eyes doesn't fit the stereotype of the bull-chested police dog, she earned her stripes in a five-week training course with Gunderson. She is now one of only 12 such dogs in Canada and her training is so good that her findings are considered admissible evidence in court.

Now four years old, the two have investigated more than 200 fires, from Tuk to Texas.

Patty stays sharp with training sessions five or six times a day, where she is tested with materials that have been dotted with liquids that could be used to start a fire.

Any owner of a smart dog knows how an animal can pick up on a behavior that earns it a treat and then fake it in order to get more treats. Although Patty is worth more than a lot of people's houses, even she has tried to slip one by her master in training, pretending to find an odor to earn a reward.

"She's tried that game," said Gunderson with a laugh, saying that the dog is caught out because she can't go to the same spot twice, or just does not react as strongly as she would to a real scent.

"It's a matter of knowing your dog and how she reacts. I know her pretty well."