We have learned that Nick Reiner was missing and unaccounted for over approximately six hours (at least) after the deaths of his father Rob Reiner and his mother Michele Singer Reiner. As we've been reporting, the famed filmmaker and his wife were found dead by their daughter Romy in their Brentwood, Los Angeles home on Sunday afternoon. Now, according to TMZ's reporting on Monday afternoon, Nick was apparently missing for hours after their deaths and before police were able to track him down.