Stalf's and Solonia Caelia's corpses didn't clean up properly. They are still there after visiting the dungeon a second time, well after finishing the Dawnguard questline. Both are being held in aliases, which is probably why.
Papyrus output - Stalf
Spoiler:
DLC1VLCrimeScript:
Script state = ""
::DLC1VampireBeastRace_var = DLC1VampireBeastRace (0200283A)
::DLC1VampireFaction_var = (02003376)
--- Papyrus - Alias StalfAlias on Quest DLC1DialogueVampireCuredBlock (0201693F)
No papyrus scripts attached
--- Papyrus - Alias StalfAlias on Quest DLC1DailgoueVampireBase (02004E0C)
DLC1ClearDrinkingOnCombat:
Script state = ""
::OffsetStop_var = OffsetStop (0008C0A0)
Papyrus output - Salonia
Spoiler:
DLC1VLCrimeScript:
Script state = ""
::DLC1VampireBeastRace_var = DLC1VampireBeastRace (0200283A)
::DLC1VampireFaction_var = (02003376)
--- Papyrus - Alias SaloniaAlias on Quest DLC1DialogueVampireCuredBlock (0201693F)
No papyrus scripts attached
--- Papyrus - Alias SaloniaAlias on Quest DLC1DailgoueVampireBase (02004E0C)
DLC1ClearDrinkingOnCombat:
Script state = ""
::OffsetStop_var = OffsetStop (0008C0A0)