Tilda Addison is the mother of the murder victim Jared Addison.
She suffered from severe OCD, everything she did seemed to come in twelves. When her son overcame his OCD and was ready to take hold of his own professional life, move out and marry, Tilda's patterns snapped and she murdered her own son with a shovel. She cut him into twelve pieces and dumped him in a pond. The head didn't fit so she buried it in her garden. She tried to frame her son's lover for the murder.
The murder was solved by Zach Addy. Booth and Brennan arrested Tilda.