Are DNA profiles from solved cases maintained in CODIS and compared to profiles from unsolved cases? Does this occur in situations where the solved case involves the DNA profile of a deceased individual who was never arrested or convicted of an offense requiring submission of a DNA sample?

Yes, to both questions.  Once a case is solved and the evidence DNA profile is associated with an individual, that profile will continue to be compared to profiles from unsolved cases.  Further, whether the associated individual is deceased or not, the evidence profile from the solved case will be compared to newly uploaded profiles from unsolved cases as they are entered in CODIS.  This occurs whether an associated deceased individual was ever convicted or arrested for an offense requiring submission of a DNA sample or not.