Bank Tellers Increasingly Involved in Identity Theft, Prosecutor Says One victim had thousands of dollars stolen from her account before her wedding.

 -- Identity theft is a growing problem across the nation, and Manhattan’s top district attorney says that bank tellers are increasingly involved, adding that his office prosecutes one case per month involving tellers.

The tellers in question are part of larger identity theft rings, District Attorney Cyrus Vance said in a recent interview with ABC News’ Rebecca Jarvis.

“Bank tellers have access to very confidential data ... they’re selling to that to individuals on the outside, who will then take that information and turn it into credit cards or checks,” Vance said.

Asked whether people around the country should be worried, Vance replied: “I think we should all be worried. That doesn't mean we should all panic.”

One victim who did not want to be named because she said she continues to be an identity theft target told ABC News that she had thousands of dollars stolen just weeks before her wedding.

The woman said she had no idea that a bank teller had stolen her identity -- along with the identities of 28 fellow customers -- until she received a letter from Chase Bank informing her of the alleged theft.

The letter said, in part: “A former employee may have accessed your account information without authorization and gave it to someone outside of Chase.”

As soon as the incident was discovered, Chase notified authorities, fired the employee and reimbursed the affected customers, the bank told ABC News.

Not all banks aggressively fight and report this type of crime, Vance said.

“I think some banks need to be doing more ... if it's not reported to law enforcement, it's just an invitation for that criminal to keep the money and go onto the next account or next bank,” he said.

The American Bankers Association -- the group that represents bankers around the country -- told ABC News in a statement that banks use many safeguards to prevent fraud, “including sophisticated software to monitor employee access of customer accounts … customers are always protected against fraud. The bank will cover any loss.”