Just a few weeks before becoming ill in June, Kneebone sang Marcello in La Bohme with the Baltimore Opera Company. The Inquirer quotes Kneebone's mother as saying he sang Marcello more than 60 times, and it was the role with which he made his 1990 New York City Opera debut.
He was more interested in baseball than music while in high school, but at Moravian College choose the school choir over baseball, according to the Inquirer. It was there that he began studying voice seriously. After receiving his bachelor's degree, he taught English at Quakertown High School for a year, then joined the Philadelphia Singers and the chorus of the Philadelphia Opera Company. He went on to do graduate study at the Academy of Vocal Arts in Philadelphia. He also sang professionally at local churches. In 1985, he was a regional winner in a Metropolitan Opera Company competition, one of several singing competitions he won.
Kneebone appeared frequently with the New York City Opera and Baltimore Opera Company and also sang with Florida Grand Opera. Recently, he took the role of Jokaanan (John the Baptist) in Salome with Michigan Opera Theater in Detroit. Other roles in his repertoire included Scarpia in Tosca, Sharpless in Madama Butterfly, Zurga in Les Pê_cheurs de perles and Count di Luna in Il trovatore.