Thieves have netted thousands of dollars in a scam targeting rural people who use their mailboxes to send cheques.
Thames Police yesterday used Facebook to warn people in rural areas not to send cheques using the gate mail pickup system, where their outgoing mail can be picked up by rural posties, and to consider internet banking.
Sergeant Jared Thompson said an "organised group", possibly gang-related, was targeting rural letterboxes with their flags up looking for letters addressed to organisations like the Inland Revenue Department.
"This particular group are going around and will stop at mailboxes with the flags up. They will quickly go through all the mail to find the one that obviously contains cheques and then they'll steal it."
Mr Thompson said the cheques were then washed using chemicals that remove the pen ink but leave all the other details on the cheque before writing a new amount and payee.
Inquiries show a member of the group will then try their luck at different banks where they try to present the cheque to an inexperienced staff member they hope will make a mistake and cash it.
"If it is one that has been crossed manually they can make it out to cash or they can use a mule, which is usually someone who has been suckered into using their bank account," said Mr Thompson. "They will have that person deposit it into their bank account and draw the money out."
He could not provide an exact figure of how much the scam had netted but said the amount was "thousands of dollars" including one transaction where a fraudster was successful in cashing a cheque for $12,500.
Several other cheques of a similar amount have been declined at different banks around the Thames area.
Mr Thompson said the group had been targeting people who do not use internet banking and were set in their ways in areas north of Thames and in the Ngatea/Turua areas over the past two months.
He suggested people not au fait with the technology quickly get themselves up to speed or use alternative methods to send mail containing cheques.
Police are reviewing CCTV footage at a number of banks.