Of three dramatic art thefts in the last months of 1978, only one has been recovered Three Monet paintings were stolen from the Santa Barbara Museum by the chief of security who returned them two days later. The chief suspect of the theft of three Cezanne paintings from a locked storage area at the Art Institute of Chicago is a former shipping clerk at the museum who left his job the day the paintings were discovered missing. The theft of a Rembrandt and other Dutch pietures at the M. H. deYoung Museum in San Francisco, however, was an outside job, the thieves having climbed to the roof and entered the museum through a skylight. -- AATA