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DENVER — The city and county of Denver continues cracking down on a surge of short-term rentals. Denver has been using the threat of felonies to enforce regulations surrounding properties that are rented out by their owners using services like Airbnb and VRBO. At least four homeowners have already been charged.

The Problem Solvers got an exclusive look inside the investigative work. FOX31 was the only TV station to receive a behind-the-scenes look — navigating what’s legal and what’s not.

The Problem Solvers followed a Denver Excise and Licenses investigator going door to door in the Highlands asking neighbors questions surrounding the permanent residency status of homeowners at Airbnb locations.

Critics say the short-term rental industry is turning neighborhoods into a patchwork of true homes and homes doubling as hotels. The city says people were buying homes not to live in, but for the sole purpose of building short-term rental portfolios.

In 2017, Denver started cracking down — saying homeowners could only list their primary residence.

Earlier this year, Denver Excise and Licenses beefed up enforcement. The department asked hosts to sign an affidavit or lose their license. That affidavit requires the host to promise — under threat of felony — the home they’re renting out is indeed their primary residence.

“The affidavit only goes out to people when we’ve got questions,” said Ashley Kilroy, executive director of Denver Excise and Licenses.

Hosts who create some sort of suspicion are targeted by the affidavits. Kilroy says, when asked to sign, some 200 hosts decided to simply give up and leave the market. 

So far, 49 people have signed the form. Of the 49, four people have been charged with felonies. 

Kilroy believes Denver is unique in using the affidavit model.

The enforcement work begins inside the Webb Building downtown. A city inspector showed FOX31 how he starts with the background work. On a map, he can sort through licensed rentals and illegal listings. The city contracts a third-party firm to search websites for properties that are not licensed. Inspectors also do the legwork on neighbor complaints generated through 311.

When FOX31 tagged along, the city investigator followed up on a 311 tip that a homeowner in the Highlands actually lives on the East Coast. The city suspects he is illegally renting out a second home in the Highlands.

Kilroy says investigations help protect the integrity of Denver neighborhoods. Denver estimates nearly 77 percent of all current online listings are now licensed.

Over the last year, new regulations decreased the total number of listings by 15 percent. Citywide, there are nearly 2,700 licensed short-term rentals.

Denver defines a short-term rental as any term less than 30 days. People can still buy multiple homes and rent them on a monthly or yearly basis.