A Barclays employee notified the Federal Reserve Bank of New York in April of 2008 that the firm was underestimating its borrowing costs, following potential warning signs as early as 2007 that other banks were undermining the integrity of a key interest rate.

In 2008, the employee said that the move was prompted by a desire to “fit in with the rest of the crowd” and added, “we know that we’re not posting um, an honest Libor,” according to documents that the agency released on Friday. The Barclays employee said that he believed such practices were widespread among major banks.

In response, the New York Fed began examining the matter and passed their findings to other financial authorities, according to the documents.

But the agency’s actions came too late and failed to thwart the illegal activities. By the time of the April 2008 conversation, the British firm had been trying to manipulate the interest rate for three years. And the practice persisted at Barclays for about a year after the briefing with the New York Fed.

Friday’s revelations shed new light on regulators’ role in the rate manipulation scandal. The documents also raise concerns about why authorities did not act sooner to thwart the rate-rigging.