Ishii switched the transfer address for a Sony Life transaction to use a Silvergate Bank account under his control.
Ishii later converted the stolen funds into more than 3879 bitcoins
After converting the money to cryptocurrency, Ishii also tried persuading his supervisor and several Sony Life executives not to help investigators by emailing them a ransom note typed in English and Japanese.
"If you accept the settlement, we will return the funds back. If you are going to file criminal charges, it will be impossible to recover the funds," the note read.