A businessman and a former White House military aide cheated prospective immigrants out of more than $15 million that was supposed to help rebuild New Orleans after Hurricane Katrina, a federal jury in Louisiana concluded.

William Hungerford and Timothy Milbrath were convicted Sept. 6 of various crimes related to NobleOutReach LLC, a company they formed to operate the New Orleans Regional Center.

The center was an investment vehicle approved under the EB-5 immigrant investor program, which provides green cards to foreign nationals who invest at least $500,000 in a commercial enterprise that creates at least 10 U.S. jobs. Regional centers,...