At about 3 a.m. on 5 April 1956, Riesel was walking north on Broadway with his secretary and a friend when, outside the Mark Hellinger Theatre, a man suspected to be Abe Telvi threw acid in Riesel's eyes. According to witnesses, Telvi stood there for a moment to assess his work, then "ambled away". (Telvi would be found dead with a bullet to the head on 28 July.) It was believed that the attack was ordered by the Genovese crime family in retaliation to Riesel's "clean union" advocacy, which included a radio broadcast he made earlier that evening criticizing the corruption of the Long Island local of the International Union of Operating Engineers. As a result of the attack, Riesel was permanently blinded.