Complex sentence: With reports that he was due to be arrested any day, Ponzi surrendered to federal authorities on August 12 and was charged with mail fraud for sending letters to his marks telling them their notes had matured.
Split into simpler sentences: With reports that he was due to be arrested any day, Ponzi surrendered to federal authorities on August 12. He was charged with mail fraud for sending letters to his marks telling them their notes had matured.