SALEM, Ore. — Astute Girl Scouts notified Salem police of a man using fake $20 bills to buy one box of cookies and get real currency for change.

Two separate scout troops reported the man and the counterfeit money to police in mid-February, according to Lt. Debbie Aguilar of the Salem Police Department.

One of the incidents occurred on Feb. 16 at the Walmart on Lancaster Drive in Salem. Ava, a 13-year-old scout, spotted the counterfeit money.

"I kept looking at it and I was like, there's no way this is the same, this does not feel right," said Ava, who waited until the man left to alert her mom, who called Salem police.

"He was intimidating and I didn't want to say anything," Ava said. "I didn't know if he could be aggressive."

Counterfeit money girl scouts
Can you spot the counterfeit bill?
Ava's Family

With assistance from Walmart security, police were able to scan surveillance video and identify the suspect. He was spotted returning to a store on Sunday, arrested and taken to jail.

Camden Ducharme, 36, faces charges of first-degree forgery and third-degree theft.

Girl Scouts in Salem nab man using counterfeit bills to buy cookies
Camden Ducharme

Aguilar thanked the scouts and the store for helping to nab Ducharme.

Ava's mother said her daughter is a "rockstar" for spotting the fake money.

"What is important is Ava's learning from it and she's helping others because of it," said Ava's mother, Tiffany.

Ava reached out to Wells Fargo Bank to learn more about detecting counterfeit money. The bank donated counterfeit money detector pens for the whole troop. Ava plans to make a training video to help other Girl Scouts.

"That's one of our Girl Scout mottos," said Ava. "To make the world a better place."

RELATED: Girl Scouts take cookie sales into the digital age