"The case made us very surprised. In Cambodia this is unusual for us," Cambodian police spokesman Kirth Chantharith told dpa.
The case came to light police learned that the suspect allegedly was deceiving them out of most of the money paid for their body parts.
According to one complainant, "she promised to pay $11,000-15,000" for a kidney, but ended up giving the donors about $6,000 each instead, Mr Chantharith said.
"I checked how could she know who is staying in hospital in Thailand and she said she got information from hospital translators," Mr Chantharith said Tuesday.
The 29-year-old was arrested July 2, The Cambodia Daily reported last week. Under Thai law, transplant donors must be blood relatives or a spouse for more than three years, the paper said.
The alleged broker's stepfather was also arrested on charges of helping the donors secure fake identity documents showing kinship with the patients, the report said.