Seniors hold more than $17 trillion in assets, and con artists know it.

"They know where the money is, and they're going after it," said Hubert Humphrey III, the former Minnesota attorney general who heads the Office of Older Americans at the U.S. Consumer Financial Protection Bureau.

Humphrey was part of a Commerce Department news conference Tuesday to urge banks and credit unions to step up the fight against an epidemic of senior fraud that costs seniors around the country an estimated $2.5 billion a year. Tellers working on the front lines frequently can spot scams before others do, Commerce Commissioner Mike Rothman said.

The event, held at the Lyngblomsten assisted living facility in St. Paul, comes after guidance that Commerce issued last week to financial institutions on identifying and reporting scams. The guidance reminded banks and credit unions that they are not bound by rules regarding the privacy of consumer financial information when it comes to senior fraud.

The law contains numerous exemptions, it said, allowing financial institutions to call authorities if they suspect a senior is being victimized. State law also grants lenders immunity from liability in those circumstances.

Terri Maloney, president of Catholic United Financial Credit Union, said it was a useful reminder.

"People in my industry need to be trained," Maloney said during her remarks. "If we spot something that looks fishy, we can work with law enforcement to make sure that our members, and their money, are safe. We have the authority and the ability to act."

Signs of a potential swindle include uncharacteristic attempts to wire money, a sudden change in who manages an older person's money, frequent large withdrawals and the closing of certificates of deposit or accounts without regard to penalties, according to Commerce.

In an interview, Tessa Rice, general counsel of the Minnesota Bankers Association, said her group has been educating its members with videos and brochures on identifying and reporting senior fraud for some time.

"Minnesota law provides immunity to those reporting potential financial crimes, so banks generally are comfortable reporting potential senior fraud to their county adult protective services," Rice said.

Most financial scams against seniors go unreported, Rothman said. For instance, no one intervened when Peggy Hiestand-­Harri's elderly mother suddenly began wiring money to Jamaica in 2010.

Hiestand-Harri, who lives in Duluth, spoke Tuesday about how fraudsters coached her mother to take cash advances from two credit cards and send $47,000 to a Jamaican scam. The mother visited local banks and credit unions at least 17 times over 10 days to withdraw money. In one visit she took out $10,000.

"It was incredibly easy. Not once was she stopped along the way," Hiestand-Harri said. "For our family it was a year of heartbreak as we tried to help our mother."

Her mother had to file for bankruptcy at age 83, she said.

Better education on the front lines might have prevented it, she added.