On June 30, 2004, Kushner was fined $508,900 by the Federal Election Commission for contributing to Democratic political campaigns in the names of his partnerships when he lacked authorization to do so. In 2005, following an investigation by the U.S. Attorney's Office for the District of New Jersey, U.S. Attorney Chris Christie negotiated a plea agreement with him, under which he pleaded guilty to 18 counts of illegal campaign contributions, tax evasion, and witness tampering. The witness-tampering charge arose from Kushner's act of retaliation against William Schulder, his sister Esther's husband, who was cooperating with federal investigators against Kushner. Kushner hired a prostitute he knew to seduce his brother-in-law, arranged to record a sexual encounter between the two, and had the tape sent to his sister. He was sentenced to two years in prison. He served 14 months at Federal Prison Camp, Montgomery in Alabama before being sent to a halfway house in Newark, New Jersey, to complete his sentence. He was released from prison on August 25, 2006.