A senior National Bank manager was arrested on Tuesday evening over the loss of Sh2.3 billion.
Dennis Oduor, the head of medium business, will be arraigned on Wednesday.
Banking Fraud Unit police chief Ngatia Iregi declined to comment on the matter.
In May, two of the lender’s former managers were arrested over the loss of Sh106 million.
Chris Kisire and Wycliffe Kivunira were charged with abuse of office and breach of public trust.
Kivunira had taken over from Kisire following the 2016 financial crisis at the bank.