Two American brothers of a Mexican casino magnate who fled drug and fraud charges in the United States and has been seeking a pardon enabling him to return have emerged as major fund-raisers and donors for President Obama’s re-election campaign.

The casino owner, Juan Jose Rojas Cardona, known as Pepe, jumped bail in Iowa in 1994 and disappeared, and has since been linked to violence and corruption in Mexico. A State Department cable in 2009 said he was suspected of orchestrating the assassination of a business rival and making illegal campaign donations to Mexican officials.

When The New York Times asked the Obama campaign early Monday about the Cardonas, officials said they were unaware of the brother in Mexico. Later in the day, the campaign said it was refunding the money raised by the family, which totaled more than $200,000.