ELKHART — The list of counterfeit complaints is growing as Elkhart Police investigate a new round of bad bills. The reports have come in from across the city that counterfeit money is being passed off at gas stations, restaurants and now even a city run pool.

Police are working with the FBI and Secret Service to track down those responsible. They're also sending out a warning to other businesses, hoping to keep others from becoming victims, too.

All the notes passed so far have been $20 and $50 bills, adding up to about $300 total. Elkhart Police say it's likely there are more fakes floating around that haven't been picked up yet.

It's one reason why Rebecca Doolittle isn't taking any chances.

Her sales these days come with a new requirement.

"Every $20, $50 or $100 that comes into my store, needs to be marked," she said, pointing to the now familiar black felt pen with ink inside that can sniff out a counterfeit bill. "We're using the marker on every bill. And the minute it turns the color it isn't supposed to, we're turning it in and the police will be called."

There's a good reason for her extra precaution.

Two days ago, the Admiral gas station she manages on Mishawaka Avenue on Elkhart's southwest side got "scammed" in what is quickly growing to become a small counterfeit ring.

"I just happened to be counting [bills from the register], and just noticed it," Doolittle said. "The paper definitely wasn't right. It was just too smooth. Nothing was raised. The lapel was too green. [It didn't look right], not at all."

It's become a familiar complaint to Elkhart Police.

"The bills look good, but they don't feel good. The paper they're using isn't quality paper. They're also a bit smaller, and the texture is obvious that it's bad," said Elkhart Police Lt. Ed Windbigler.

On Tuesday, reports of fake bills began to flood in from gas stations and restaurants.

The first claim came from a McDonald's restaurant in the 1400 block of Nappanee Street.

"A man attempted to use a counterfeit $20 bill, and they caught it, and he took off," Windbigler said. "About that same time, somebody uses a couple of different $50 bills at a [Marathon] gas station on Franklin Street, and then somebody else passes a $20 bill [at the Admiral station] on Mishawaka Road."

Police hoped the list would stop there. Instead, it kept growing on Wednesday.

The same suspect went back to the same McDonald's, and then allegedly tried to pass bills at a Marathon station in the 1800 block of E. Bristol Street on two separate occasions.

The latest round of bills ended up at Pierre Moran swimming pool, one $50 bill and three $20 bills. City employees accepted the bills, then sent them in to be deposited in the city's bank account at First Source Bank.

A bank manager at First Source's downtown Elkhart location told WSBT that employees there immediately recognized the bills as fakes because of how they felt.

The bank's next call, he said, was to the FBI.

Police are now working with both the FBI and Secret Service agents from the U.S. Treasury Department to track down those responsible.

"We've got approximately 12 cases since the first of June, but six of them came in two days. It's not a common thing here. So, for us to get six new cases in two days, that's very unusual," Lt. Windbigler said.

It's left him with only one conclusion.

"It's probably the same group. There's too many of them at one time, and so, just speculation, but I would think they're all involved," Windbigler said.

It's left police asking local businesses to stay vigilant.

They didn't have to tell Misty Huber twice.

Someone tried to pass off two counterfeit $20 bills at her Burger Dairy gas station on Franklin Street four months ago. Since then, she hasn't taken any chances.

"Somebody is definitely circulating them around, and I don't want anyone else to get scammed too," she said.

She now uses the counterfeit marker on every large bill, every time.

"The fake one is going to be a dark color, and the real one is a yellowish color," she said, marking each bill. "And I look for the watermark too. And, on the newer bills, if it's a fake, it's not going to have the head on it."

There's another simple test, too.

Most newer bills will leave a green colored mark behind if rubbed against a sheet of plain white paper.

"They have a special imprint ink in them that counterfeit bills won't have," Windbigler said.

They are important steps, police say, if for one simple reason.

"If he's hit this many places, we'll probably get more cases in," Windbigler said.

It's one reason why Doolittle's motto now is "better safe, than sorry."

"I've got my clerks good and trained, and they'll catch the next one," she said.

Police only have a vague description of one of the suspects in the counterfeit scheme. He's described as a black male, 35-40 years old with a gray-ish beard. He was last seen driving away from the McDonald's on Nappanee in a dark colored SUV.

If the suspect is caught, Windbigler says it's likely he'll be turned over to the U.S. Secret Service, where he could face federal felony counterfeit charges.