It seems like they don't know.

"The target of the scam was convinced that he was speaking with his boss due to a “subtle German accent” and specific “melody” to the man’s voice and wired the money as requested.

According to a representative of Euler Hermes Group SA, the firm’s insurance company, the CEO was targeted by a new kind of scam that used AI-enhanced technology to create an audio deepfake of his employer’s voice. " - https://cyberscout.com/en/blog/voice-deepfake-scams-ceo-out-...

its a random assumption / hypothesis. maybe even it was the real ceo... :D that'd be too funny

Be an effective way to get some money.

Alan Turing would like to know as well...