Victoria Will/AP Photo "Sesame Street" muppet Elmo and puppeteer Kevin Clash pose for a portrait in the Fender Music Lodge on Jan. 24, 2011. NEW YORK (AP) - The puppeteer who performs as Elmo on Sesame Street is taking a leave of absence from the popular kids" show following allegations that he had a relationship with a 16-year-old boy. Sesame Workshop says puppeteer Kevin Clash denies the charges, which were first made in June by the alleged partner, who by then was 23. MORE: Sesame Street's Elmo Talks To Kids About Hurricanes 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 has voiced and animated Elmo since the 1980s. MORE: TIME's Q&A with Kevin Clash, the Man Behind Elmo