Officers believe a money laundering and fraud scheme connected to the sale of puppies in south Norfolk may date back up to seven months.
Six people were arrested on Wednesday morning in connection with the crimes.
Four men and women in their 20s and a man and a woman in their 30s were both taken into custody across five homes in the Trowse and Loddon areas.
They were questioned at Wymondham and released under investigation while the probe continues.
One puppy recovered from one of the homes is being looked after by the RSPCA.
Norfolk Police said some victims have already spoken to officers investigating the alleged crimes, and is encouraging more to come forward.
Anyone who thinks they may have been a victim of the fraudulent sale of puppies in south Norfolk since December 2020 is encouraged to contact the police.
Any potential victim or anyone with information should contact PC Charlie Stone on 101 quoting investigation number 36/45855/21.
Alternatively, call Crimestoppers on 0800 555 111.
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