This is a variation of an old effect named Peppers' Ghost.  

For the performance of this illusion an audience member is selected at random and seated behind Dorian's frame. The magician lights a candle and strange things begin to happen.  The magician steps back and watches the transformation along with the audience. He then lights the second candle and the participant becomes a skull which the magician removes from the frame. Meanwhile, the audience member still seated no longer has a head. Upon placing the skull back in the frame and extinguishing the candles the spell is reversed.