Iowa City - The president of a Christian charity in Iowa admitted that he embezzled nearly a half-million dollars in donations and used the money to pay for a sex addiction, federal prosecutors said on Tuesday.Jon S. Petersen, of Cedar Rapids, pleaded guilty on Monday to one count of filing a false tax return. He was released from custody pending a sentencing hearing, which hasn't been scheduled.Petersen, 55, is the longtime president of World Ambassadors, Ltd., a nonprofit he founded with his wife in 1993 to provide a Christian outreach to international students on college campuses.In his plea deal, Petersen admitted that he moved $475 000 in donations from the charity to his personal checking account between 2010 and 2014, draining virtually all of its funding, prosecutors said. The group had about three dozen contributors annually.A decade of addictionThe guilty plea concerned his personal 2013 tax filing, when he failed to report $114 000 diverted from the group as taxable income. The charge carries up to three years in prison, and Petersen may be required to pay restitution to the group's donors.Petersen said he struggled with a sex addiction over the last decade and used the donations to pay for it - along with credit card debt and home equity lines of credit, prosecutors said. They didn't go into detail about what he bought with the money.The IRS yanked the group's tax-exempt status in 2010 after it repeatedly failed to file a required annual disclosure on its income and spending, records show. Nonetheless, it was still registered as a nonprofit corporation and in good standing with the Iowa Secretary of State's Office.Petersen didn't immediately return a phone message on Tuesday. His attorney was out of the office and didn't immediately return an email message seeking comment.