A law enforcement offical said an announcement on the settlement could happen as early as Tuesday, according to the Associated Press.
The UK-based bank allegedly helped launder money from drug cartels and on behalf of nations under international sanctions.
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Mack entered her plea in federal court in Brooklyn. The judge refused a request by her lawyers to release her without bail.
Officers investigating a reported break-in on Friday found 22-year-old Roger Alvarado asleep in the pop star's home in Tribeca.
Billy Jeeves is said to have fled the scene in Hither Green, south-east London, after Henry Vincent was fatally stabbed by the pensioner.