Kevin Clash, Elmo puppeteer, accused of inappropriate relationship with 16-year-old boy "Sesame Street" muppet Elmo and puppeteer Kevin Clash / AP Photo/Victoria Will, file (CBS/AP) NEW YORK - Kevin Clash, the puppeteer behind Sesame Street's beloved Elmo character, is taking a leave of absence from the popular kids' show after allegations surfaced that he had a relationship with a 16-year-old boy. PICTURES: Elmo puppeteer accused of relationship with teen Sesame Workshop says Clash denies the charges, which were first made in June by the alleged victim, who by then was 23-years-old. In a statement issued Monday, Sesame Workshop said its investigation found the allegation of underage conduct to be unsubstantiated. But it said Clash exercised "poor judgment" and was disciplined for violating company policy regarding Internet usage. It offered no details. At his request, Clash has been granted a leave of absence in order to "protect his reputation," Sesame Workshop says. No duration for the leave was specified. Clash joined the show's cast in 1985, according to CBS Baltimore. His work as Elmo earned him an Emmy in 1990.