Defense lawyers for two British ex-bankers accused of manipulating worldwide interest rates to their benefit urged jurors to reject the charges against their clients in closing arguments delivered in a federal court in Manhattan Tuesday. The jury began deliberations in the trial that is being seen as a high-profile test case for the U.S. Department of Justice (DoJ).

Libor -- the London Interbank Offered Rate -- is a short-term benchmark rate banks charge each other for loans and serves as the initial step for calculating interest rates on hundreds of trillions of dollars worth of loans transacted throughout the world. It is calculated daily based on submissions by a panel of banks. Several banks, including Barclays, Deutsche Bank and UBS, have so far been forced to shell out a total of $9 billion in regulatory settlements linked to Libor-rigging cases.

Anthony Allen, 44, and Anthony Conti, 46 are charged with conspiracy and wire fraud, and of abusing their positions to influence the Libor. The two worked for Rabobank -- which, in 2013, admitted that its employees manipulated the benchmark rate and agreed to pay $1 billion to American, British and Dutch authorities. The payout also included a $325 million deal with the DoJ to allow the bank to avoid criminal prosecution in exchange for cooperation.

Prosecutors have argued that Allen -- who was Rabobank’s global head of liquidity and finance -- and Conti -- a trader on the bank’s cash desk in London -- conspired with other bank employees between 2005 and 2011 to falsely report their bank’s cost of borrowing from other banks in London so that it could gain an advantage in the financial markets.

“Year after year they ran a scam,” Brian Young, a DoJ lawyer, reportedly said, in his closing arguments, adding that the defendants had “left a paper trail a mile long.”

However, the defense lawyers rejected the accusations, arguing that the case relied on out of context emails and instant messages. 

“This is the kind of case that the more you look, the more you dig in, the more the prosecution’s case falls apart,” Michael Schachter, Allen's lawyer, reportedly said. “The pieces here don't fit together because Tony Allen is not guilty.”

The case is the first in the U.S. related to allegations of Libor-rigging and is a crucial one for the Justice Department, which has faced criticism for failing to prosecute bankers following scandals linked to the 2008 financial crisis.