KITTERY (AP) — Police are working with the Secret Service to determine who’s responsible for the recent use of counterfeit $100 bills spent in New Hampshire and Maine stores.

In Kittery, Maine, Detective Sgt. Ron Avery said an investigation of counterfeit money being taken by cashiers at retailers on Route 1 over the weekend has turned up more confirmed reports of fake money being used to buy items.

Police had turned up 19 fake $100 bills as of Wednesday afternoon and expect to get more reports.

Avery said the investigation of counterfeit money being used in Kittery began on Saturday and Sunday when police took reports from six outlet stores that individuals had purchased items with what later appeared to be counterfeit money.