GREEN BAY, Wis. -- Green Bay Police are investigating an uptick in retail thefts of Crest White Strips at local drug stores.

Police say that suspects are taking the white strips and then leaving the boxes. Employees reported finding empty boxes on the shelves.

Six different retail thefts are being investigated. The total value from the stores is $6,612.

Appleton police are also investigating thefts of whitening strips.

Green Bay Police are encouraging retailers to follow crime prevention tips.

• Stock the white strips like you do tobacco or baby formula products

• Place security devices on the strips to ensure the boxes are not opened

• Stock the strips in a location directly under a video surveillance camera

• Place the strips in a secure locker and remove upon request.

If anyone has information about the retail thefts, please contact Green Bay Police at (920) 448-3200.