D had a long history of serious mental illness. D's mother, Joan, picked up D at his apartment and brought him back to her condominium. Joan had invited some of her friends to come over to the condominium swimming pool. Worried that his mother was leaving him, D went upstairs and retrieved a crochet-covered brick, which he used to hit Joan repeatedly over the head. He then moved her body to the bathroom and repeatedly stabbed her. He informed law enforcement officers that he was preparing her body to be buried by bleeding her. Joan's death was listed as a homicide due to the multiple strikes to her head. D was arrested and subsequently indicted for Joan's murder. D was not competent to stand trial. The circuit court then committed D to remain at that facility until he was declared competent to stand trial. D is still committed. P filed a petition to probate Joan's will. Once the heirs-at-law were determined, P filed a Motion to Declare Devise Void as to D, based on the Slayer Statute. The assets of Joan's estate, exclusive of the portion assigned to D were distributed. D appealed. D argued that P had failed to prove he willfully or feloniously caused the death of Joan.