CSI: Crime Scene Investigation is preparing for some heavy character development in the second stretch of Season Thirteen.

Sources close to the show tell CSI Files exclusively that Sara Sidle (Jorja Fox), Nick Stokes (George Eads), and Morgan Brody (Elisabeth Harnois) will be dealing with some significant character development during the remainder of this season, and also potentially set the stage for a visit from returning characters.‘We want to more completely address the issue of Sara and Grissom; the challenge of that for her, certainly,’ one source tells CSI Files. That particular storyline will gain traction in this season"s tenth episode, ‘Risky Business Class,’ which is scheduled to air December 12. Ed star Josh Randall will appear (in what is being eyed as a recurring role) as a NTSB investigator that Sara previously worked with in San Francisco, the city she was employed in prior to joining Grissom"s (William Petersen) team in ‘Cool Change.’ Randall"s Doug Wilson character comes at a time where Sara and Grissom"s marriage is going through a difficult and straining time, and mere seconds after the couple try yet again to connect on the phone. ‘We have big plans for Sara,’ another source shares. ‘The audience is going to be very interested in a turn that she takes.’ Though not able to elaborate on what direction the character will be taking, CSI Files has learned exclusively that Adam J. Harrington, who played Ronald Basderic in this season"s ‘Code Blue Plate Special,’ will return and quite possibly reignite some of Sara"s anger and frustration seen earlier this year. ‘That"s going to be an interesting adventure.’

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To fill the rest of the season out: an episode that has some Latin music flavor, an odd forensics murder mystery at an all-female poker tournament that has a unique murder weapon, and maybe another visit or two from some of CSI“s iconic characters from the past. ‘There"s a possibility of a Lady Heather [Melinda Clarke] and Sofia Curtis [Louise Lombard], but the writers have stories they"re working on and it all depends on a case and story basis.’