The skeleton is identified as belonging to a (nonexistent) victim of the Salem Witch trials, a woman who was pressed to death. (No women were pressed to death at the Salem trials). They seem to assume that because she was killed in the trials she was a "Witch". An assumption no rational person could reasonably make.
The more recent body is of the owner of the house. Her brother testifies that she had taken an interest in Witchcraft. Dr Sweets finds the website of a local "Wiccan" coven and pretends to be female to get an invite to a ritual! (WTF! I have done open rituals, but not with a single gender group, not for sky clad. A closed group would meet new people on neutral ground before giving directions to a ritual.) Booth and Brennan go to the ritual but hide in the bushes to watch. The all female "Wiccan" coven burn some sort of effigy and dance naked. Booth makes a comment about unattractive people getting naked. Which is odd because all of the woman in the Coven are young and beautiful.
Booth and Brennan interrupt the ritual to ask questions and the Coven leader mentions something about the perils of practicing the "Dark Arts". It is asserted several times that the dead woman put curses on people for money, and had nothing to do with the Wiccan Coven. Except one of the coven members is descended from the Salem skeleton found in the wardrobe.
This episode was written by the forensic anthropologist Bones is based on. It was worse than I expected. I couldn't even begin to explain how many things were wrong with it. I really hoped for better from a forensic anthropologist. It looks like she did no research at all on Wicca or the Salem Witch trails. The only good thing was that they asserted that Wiccans are good...but then it turns out the whole Coven accidentally ingested rye mold and killed someone in a drug fueled frenzy. *HEADDESK*
I really prefer the way Witches are depicted in Harry Potter or Charmed. At least they don't pretend to get us involved. I've seen Wicca referenced in popular TV before where it wasn't too bad. But this was really bad.