yes Brian Muehl (correct spelling) originated the charcters of both Elmo and Telly. he was also the original performer for Grungetta too. Telly and Grungetta immediatly passed to Marty Robinson and Pam Arciero (respectively) after Brian left SS, Elmo as I'm sure you know passed on to richard Hunt and then to Kevin Clash. It's funny if you watch the A&E biography of SS when Kevin Clash talks about Richard being Elmo and giving the charcter to him. They show a clip of elmo with a different voice (I, Claudius) but it's Brian Muehl there NOT Richard! LOL
Richard did the front end of Snuffy but never actally performed the voice. The voice was always Jerry or Marty. Jerry stopped doing Snufy because of the starin on his back. So they put Richard in the suit and had Jerry voice it while they searhed for another performer. Enter Marty Robinson.
Hope this helps.
--Matt