In March 2013, a young Malaysian financier sent a heads-up to an employee at a Kuala Lumpur bank that “681 American pies” would soon be arriving from overseas.

The sender, Jho Low, emphasized the need for secrecy, according to a transcript of BlackBerry instant messages reviewed by The Wall Street Journal. The employee, he wrote, should tell the bank’s chief executive that “PM” didn’t want his name, address or identity-card number to appear on the transaction.

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