INDIANAPOLIS -- Man's best friend is aiding the search for the cause of a fire that gutted an under-construction, upscale apartment complex downtown on Thursday.

The state's only certified K-9 to work such fires was at work Sunday in the rubble of the Cosmopolitan on the Canal complex, 6News' Rick Hightower reported.

Investigators at the scene, including 20 people brought in by the Bureau of Alcohol, Tobacco, Firearms and Explosives, are tight-lipped about their work.

There is no indication whether an accelerant was used in the fire, but if there was, Bailey could detect very small amounts of fuel with his highly-trained nose.

Bailey, a 7-year-old Labrador retriever, is the only dog in Indiana certified by the ATF to detect accelerants.

"The accelerant detection K-9 is a vital part of the team," said Kimberly Riddell, of the ATF. "(He) can rule in or rule out certain areas that the investigators may want to look at."

During a demonstration Sunday, investigators showed how Bailey sniffs out burned objects searching for fuels that might have started a fire.

"He will take his nose and pinpoint within an inch. We then mark that area for the evidence tech to be able to send it off to a criminal laboratory," said Michael Wilson, Warsaw fire marshal and Bailey's handler.

Bailey also worked recent large fires in Anderson and Shipshewana. His home is with the Warsaw Fire Department.

"He started his career as a seeing eye dog, but the funny story about it is he flunked out because of his distraction to cats," Wilson said.

The apartment complex on Senate Avenue and Michigan Street, was to be home to 210 apartment residents, along with retail shops.