JACKSONVILLE, Fla. -- Even undercover investigators were surprised when more than half of those soliciting home-improvement work at a home set up to catch unlicensed contractors were not legitimate businessmen, Sheriff John Rutherford said Friday.

A six-month joint investigation between the Jacksonville Sheriff's Office and the Florida Division of Business and Professional Regulation ended with the arrest of 16 people and citations issued to 33 others accused of soliciting work without a license.

"If we can catch this many this easily, I think it's an indicator there's an awful lot of this going on," Rutherford said.

A DPR investigator and a JSO detective went undercover in a decoy house in Arlington and called people advertising plumbing, electrical and roofing services that would require a state license to come and give estimates.

Of 85 people who responded, 49 were unlicensed.

Twelve of those arrested were not booked into jail, but issued notices to appear on the charges and issued cease-and-desist orders. Four arrested were transported to jail because of other charges.

Warrants are out for two others.

"Public safety is our top priority, and by catching these unlicensed individuals, we've eliminated these situations where consumers would have been at risk," said Interim Secretary Chuck Drago. "This sting demonstrates the need for consumers to educate themselves before beginning work with a contractor."

Investigators worked with Northeast Florida Roofing and Sheet Metal Association, Jacksonville Master Electricians Association and the Jacksonville's building department to collect unlicensed individuals' advertisements for roofing and electrical services.

Rutherford said homeowners should educate themselves before hiring any contractors -- and especially before paying any money. But he also said the JSO's economic crimes division will continue to run operations like this to help protect the public.

"The message to these unlicensed contractors out there is: 'Guess what? The next home you might go to might be us,'" Rutherford said.