$10 million reward deadline approaches in unsolved art heist

(CNN)The clock is ticking on a $10 million reward for some missing artwork -- including Rembrandts, a Vermeer and sketches by Degas.

The 13 pieces of art were stolen from the Isabella Stewart Gardner Museum in Boston in a daring 1990 heist. They are valued at more than $500 million.
Initially, the museum offered a $5 million reward for the artwork. In May, the museum doubled it -- to $10 million -- in an attempt to entice anyone with information to come forw