MADISON, Wis. – A sophisticated telephone scheme that is draining funds from home equity lines of credit is spreading rapidly and has hit at least 18 credit unions in recent days, with losses mounting to more than $6.5 million.

The thieves are targeting members who have been granted large lines of credit through HELOCs, according to CUNA Mutual, which is receiving fraud claims. The thieves send a fax or email to the credit union at a call center requesting large funds or wire transfers, typically more than $100,000.

In some cases, credit union employees have followed written security procedures to include telephone call-backs to a secure phone number in order to verify the transfer requests, but the thieves have apparently made arrangements with telephone providers to have calls forwarded to their phones and have intercepted the calls. What is more baffling is that the credit union’s caller identification indicates that the call is going through to the member’s number of record.

In one such case, the HELOC thieves convinced Woodstone CU, in Federal Way, Wash., to transfer $665,000 from a members account, then the funds were rapidly wired to an overseas account.

CUNA Mutual is working with the FBI and U.S. Secret Service in investigating the case.