Complex sentence: Following the incident, Jeff went insane and cut a smile into his cheeks and burned off his eyelids he is now a serial killer who sneaks into houses at night and whispers "go to sleep" before murdering his victims.
Split into simpler sentences: Following the incident, Jeff went insane and cut a smile into his cheeks and burned off his eyelids. He is now a serial killer who sneaks into houses at night and whispers "go to sleep" before murdering his victims.