Trying to get away from a near-rape encounter, Claire was pushed and fell on a pile of spikey wood by a school big shot athelte. She was "dead", but was not murdered. Later in the morgue, she regenerated herself back to life.

Sylar did go after Claire following the incident, but killed the wrong cheerleader in the locker room. You must remember that Peter came to the rescue and therefore was able to mimick Claire's ability from then on.:D