Remember when the U.S. Treasury Department redesigned high-value bills a few years ago to help stem the illegal production of counterfeit money?

Well, criminals are back at it, or still at it as the case may be, causing some businesses in eastern Maine to refuse to accept some monetary notes.

Many Bangor area retail businesses have posted signs in their establishments warning customers they do not accept $100 bills. The currency is being rejected at gas stations, convenience stores and sandwich shops, among other businesses, largely because of fears of forgeries, according to some business owners.

John and Christine King, owners of State Street Subway in Bangor, said Wednesday they do not accept $100 bills at their sandwich shop because they are worried about getting stuck with fakes.

“It’s because of all the counterfeits going up and down the interstate [highway],” Christine King said during a brief lull between customers. “You get suspicious when people ask you for a $1.38 drink and then give you a $100 bill.”

The forged money is so believable that even special pens designed to reveal their authenticity are ineffective, she said. The possibility that a thief might be tempted to rob her shop is another reason not to accept the high-value bills.

“I don’t want $100, whether it’s fake or real or in pennies,” she said.

Employees at G&M Variety Market in Holden and at a High Street gas station in Ellsworth, both of whom asked not to be identified, said separately Wednesday that the combination of counterfeit fears and cash availability have led them not to accept the notes. Making change for a $100 bill, whether it is real or not, can result in too little cash being left in the register, they each said.

If a business unwittingly accepts a counterfeit bill and tries to deposit it at a bank, the bank usually detects it and will not count it toward the deposit, a man working at the Holden store said.

“I’m out the $100,” the man said. “That’s why store owners have decided to [not accept the bills.] It hurts business.”

Fran Fruchtenicht, vice president and security officer for Bangor Savings Bank, said Wednesday that a rash of counterfeit $100 bills appeared in Maine in March but that since then the number of fake bills being detected has dropped off.

“It’s been a while since I’ve seen any,” she said. “It’s really died down.”

When the bank’s branches come across patterns of illegal financial activity, they individually pass the relevant information on to customers, according to Fruchtenicht. It is up to the customers to decide whether they want to take precautions.

“We don’t make any recommendations,” she said. “What they do with [the information] is their business.”

Jane Madigan of Merrill Bank said Wednesday that its branch at the corner of Stillwater Avenue and Hogan Road in Bangor sent out a notice to its customers in March when it found three counterfeit $100 bills in its deposits. She said she has not heard of any counterfeit bills being detected since then.

Jere Armstrong, chairman of Maine Bankers’ Association security committee, said Tuesday that there generally is more counterfeit currency in Maine this time of year. This is not because of any spike in criminal activity, he said, but simply because the start of the summer tourist season brings more cash of all kinds into the state.

“With technology today, it’s easy to print anything,” Armstrong said. “I don’t see any [increased threat]. Counterfeit currency has been out there since the Civil War.”

Armstrong said there are other more pressing currency issues that should concern the public. Worthless Saddam-era Iraqi money is being pawned off in Maine as having monetary value, he said, and Mainers should be aware that Mexican currency has an expiration date.

“I’d be more concerned about that,” he said.

Armstrong said that rather than not accepting $100 bills, retail business owners should educate themselves and their employees about how to spot counterfeit currency by visiting the U.S. Secret Service Web site on the Internet. Businesses that don’t accept the bills are deciding to do so on their own, not because of any official alert or advice, he said.

“Anybody accepting currency should be familiar with all the security features put into the new currency,” he said.

Ellsworth police Detective Dotty Small has a counterfeit $100 bill that she keeps in a clear plastic sleeve tacked to a bulletin board in her office. Small, who has had the bill since 2001, said Wednesday that she had heard complaints in recent months about fake money being passed at local establishments.

“There are several [businesses] that don’t” accept $100 bills, she said.

Small recommended that people check the serial numbers of bills they are offered. Forgers often make several counterfeit bills from one real note, printing the same serial number on each copy, she said.

Sgt. Paul Kenison of Bangor Police Department said Wednesday that his department has no active cases about counterfeit money. All information about counterfeiting crimes is passed on to the Secret Service, he said, but the local police department often participates in the resulting investigation.

Business owners have to decide individually whether it is in their interests to accept $100 bills, he said.

“You have to put in a certain amount of moderation in everything,” Kenison said. “Unfortunately, we live in a society where you have to be cautious.”