CLEARWATER — He sounded like just another tourist calling to rent a waterfront vacation home.But really, this was good old-fashioned detective work.Constantine Janus, private investigator, had been surveilling this three-bedroom house in Island Estates for days. He had crept by twice already to snap photos of the out-of-state cars in the driveway.Now with a phone call posing as a potential customer, he was about to help his client — the city of Clearwater — crack down on one of the area's most problematic black markets. Short-term rentals.• • •It is illegal in Clearwater to rent out a home for less than a month, but with tourists gladly shelling out thousands of dollars a week for beachfront stays, an illicit rental market is thriving. The work it takes to document violations has overwhelmed the city's code compliance department. So they brought in a professional.For his first case in August as the city's spy, Janus called the number listed on VRBO.com for the home at 360 Palm Island NE. The owner had already been given three warnings after neighbors complained about guests coming in and out weekly. Janus told the listed owner, Dan Chiavatti, he had family coming into town and wanted to rent a house for two weeks."Dan told me he would rent the property for the two-week period for $3,200 plus $100 for cleaning," Janus reported to the code enforcement board Sept. 30. "I told Dan I would speak to my family and get back to him in a couple of days."The code enforcement board swiftly found Chiavatti guilty. The next violation will cost him $250 a day."They have their laws they have to go by," Chiavatti said in an interview Friday. "I understand."• • •Clearwater's current short-term rental ordinance has been in place since 2003, but code compliance manager Terry Teunis said his department has doubled down on enforcement this year as the law is increasingly ignored.The department previously had only one officer assigned to investigate the hundreds of leads on violations, among her other responsibilities.So frustrated residents in high-target neighborhoods, mostly the beachfront communities, had joined forces to photograph the revolving door of visitors at certain homes and submit evidence to the city."This is a neighborhood, not a hotel," said Samuel Hutkin, whose neighbors in North Beach tip off the city on violators. "We've had neighbors that have just had so many issues with noise until all hours, trash, disrespecting the beach."Hutkin, also on the board of directors of the Clearwater Beach Association, said people so blatantly break the law that investors commonly buy foreclosed homes for the sole purpose of renting them by the week.But evidence has to be solid for the code enforcement board to be able to issue fines. Many times, Teunis said, violators who are caught by the city advertising their homes online as week-to-week rentals pull the ads during the city's reinspection period, giving officials no choice but to close the case.Teunis said another common trick is for homeowners to instruct their renters to tell suspicious city inspectors they are family or employees of the homeowner staying in town for business. "They're very sneaky in what they do," Teunis said. "They're very creative."There have been 23 short-term rental cases brought before the code enforcement board so far this year, compared to just a handful in 2014. All but two of those were found in violation and three resulted in fines: $9,000, $500 and $5,500 respectively. But Teunis said they could nail even more with the right evidence.Enter Constantine Janus. Private eye.• • •Janus, 71, spent his law enforcement career investigating crimes for Pennsylvania's Department of Revenue and Office of Inspector General. He helped bust a ring of people who rigged the daily lottery in 1980 by weighting all the balls in the wheel except for three numbers. He investigated check fraud, political corruption and organized crime.In 1996 he decided to retire to Florida. But five years ago, the investigating itch came back.Since opening his firm in Clearwater, he has mostly worked missing person and financial abuse cases, along with tracking people who can't be found to be served with legal papers.It is not uncommon for municipalities to hire detectives for odd jobs. Middletown, Conn., officials hired a detective last year to catch a police officer working at his auto business while on disability leave.Four government officials in Jacksonville were suspended in 2010 after a private investigator hired by the county filmed them partying at a hotel instead of attending taxpayer funded hurricane preparedness training — one was caught stumbling naked on a balcony, the Florida-Times Union reported.Clearwater pays Janus $40 an hour for his investigation of short-term rentals, assigned on a case-by-case basis.He'd like to think his snooping has had an impact.On Wednesday afternoon, Janus cruised by the Palm Island NE home with his camera to see if any tourists looked like they were crashing there again after Chiavatti's warning in September. The driveway was empty, and he snapped a photo as evidence. "Oh, no one there," he said. "Good."Times staff researcher Caryn Baird contributed to this report. Contact Tracey McManus at [email protected] or (727) 445-4151. Follow @TroMcManus.