New York State police in Dutchess County arrested a 56-year-old woman for grand larceny, forgery and scheme to defraud.
Theresa Frederick, of Greenport, allegedly sold a Pomeranian puppy and forged documents regarding the dog's health and vaccinations.
State police say there is reason to believe there could be other victims.
Police are asking residents to stay vigilant when making any type of purchase online.