In 1994, Harp's family paid about $30 million after he was held for 106 days by his kidnappers in Mexico City. The release followed a dramatic television appearance in which his son, accompanied by a family Lawyer and a priest, accepted the kidnappers' terms unconditionally. At the family's request, the police did not intervene, giving rise to fears that the huge ransom would encourage more kidnappings, and adding to concerns about Mexico's stability. In 1996, authorities claimed to have recovered nearly $10 million of the Harp ransom.

Born in Mexico City, Harp is most famous for being the former owner of the biggest Latin American and Mexican bank, Banamex (now part of Citigroup), and was a billion-dollar beneficiary of Citigroup's 2001 buyout of Banamex. He is also owner of the Telecommunication company, Avantel, the second largest telephone company in Mexico (now part of Axtel).

In 2008, Harp attended the funeral of Fernando Martí, 14-year-old son of the founder of a chain of sporting goods stores, who had been kidnapped and murdered, despite his family's payment of a ransom. He also paid for a full-page advertisement in newspapers calling on the government to put a stop to the rising kidnapping phenomenon in Mexico.