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Embattled Wells Fargo is accused of adding on to fraud victims' troubles by closing their accounts without investigating potential criminal activity, a new lawsuit by an ex-fraud investigator for the bank claims, echoing customer complaints.

By law, a bank is supposed to investigate potential criminal activity when a customer complains of fraud. Instead, according to Matthew Valles, who worked as a fraud investigator for Wells Fargo in Portland, Oregon, the bank closed the accounts and got rid of the customer. On Wednesday he sued the bank and his former manager for violating whistleblower laws, alleging he had been fired in retaliation for his complaints about "hundreds" of mishandled cases.

Valles said he was newly transferred to the fraud unit when he discovered an internal culture whose "directive" was to "meet Wells Fargo’s metrics at all costs."

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"When Wells Fargo customers experienced fraud or unauthorized activity on an account, Wells Fargo failed to adequately investigate the fraud, and instead closed the account under the pretext of a 'business decision,'” the suit claimed.

"Improperly closing customer accounts in this manner ensured that customers, not Wells Fargo, were left to absorb the costs of fraudulent activities and unauthorized withdrawals from their checking and savings accounts," it said, which could harm customers' credit if the fraud caused their account to become overdrawn.

Wells Fargo customers have filed consumer complaints with the Consumer Financial Protection Bureau alleging the same behavior, but Valles, in his suit, is the first former employee to corroborate their claims.

The bank has been under extreme pressure to reform in the wake of a massive unauthorized customer fee scandal that found their old CEO John Stumpf testifying before Congress and ultimately led to his sudden retirement and that of another executive.

For more, watch NBC Nightly News with Lester Holt tonight at 6:30 PM ET.

The bank later paid $110 million to settle a class-action lawsuit arising from the outcry and paid $185 million to federal and California authorities.

Earlier this year, the Federal Reserve severely sanctioned the bank, barring it from growing further until its problems were fixed.

"We take seriously the concerns of current and former team members and investigate them thoroughly. Our goal is to protect our customers and the bank from fraud, and we want to do so in ways that minimize the risk and impact on our customers," Jim Seitz, a Wells Fargo spokesman, told NBC News in a statement.