BUENOS AIRES  The mystery of who revealed Gov. Mark Sanford’s e-mail messages may finally be solved. A business associate of Mr. Sanford’s Argentine mistress said Friday that private messages between the two lovers had been sent anonymously to a South Carolina newspaper last December by an Argentine man the mistress had briefly dated.

The associate, who asked not to be identified, is a Buenos Aires television executive involved in hiring the woman, whom he identified as María Belén Chapur, a producer at the television network America from 2001 to 2002.

Last December, the executive said, Ms. Chapur was dating a young Argentine a few months after her affair with Mr. Sanford began. The man happened to see the e-mail messages being exchanged between the governor and Ms. Chapur, said the executive  who said he had direct knowledge of the situation  and hacked into her e-mail account to see the rest.

Infuriated, the man sent the messages to The State, the newspaper in South Carolina’s capital, Columbia.