In the June 10, 2013 edition of The New York Times, business reporter Jessica Silver-Greenberg tells the story of Bruno Koch, 83, in Banks Seen as Aid in Fraud Against Older Consumers. Mr. Kirby told the telemarketer on the line that, yes, of course he would like to update his health insurance card. Then Mr. Koch, of Newport News, Va., slipped up: he divulged his bank account information.

What happened next is all too familiar. Money was withdrawn from Mr. Koch’s account for something that he now says he never authorized. The new health insurance card never arrived.

What is less familiar — and what federal authorities say occurs with alarming frequency — is that a reputable bank played a crucial role in parting Mr. Koch from his money. The bank was the 140-year-old Zions Bank of Salt Lake City. Despite spotting suspicious activity, Zions served as a gateway between dubious Internet merchants and their marks — and made money for itself in the process, according to newly unsealed court documents reviewed by The New York Times.

Lawyers at Langer, Grogan & Diver sued Zions, representing several hundred thousand consumers who said that NHS Systems and other telemarketers took money from their accounts without authorization. The lawsuit, which is pending in a federal court in Pennsylvania, claims that Zions effectively gave “fraudulent marketers direct access to every bank account in the United States.”