His first question on Tuesday's show: Does the couple, whose daughter Casey was acquitted of murdering their granddaughter, Caylee, believe that she was involved in the infant's death?
"Well, the last one I saw Caylee with was Casey," George replied. "To me, in my mind, that one and one adds up to two. She's responsible for Caylee – that's her daughter."
Pressed by McGraw to elaborate on what his definition of "two" is in this equation, George added, "Casey and Caylee, when I saw them leave on June 16, 2008, [that] was the last time I saw them together. And Casey, again, is responsible for Caylee no matter where she was at or what happened."
Cindy Anthony, whom McGraw has referred to as "very much in denial," was less willing to call her daughter out on her admitted bad behavior, including lying, deception and theft.
She and her husband admitted Casey stole from their wallets and even their gas cans, but put forward a new theory on her daughter's troubled actions, saying a variety of illnesses could be responsible.
"I want to find out what's wrong with Casey," she told the TV doctor. "I know there's something wrong. She had a grand mal seizure after she came home [from prison] after the first time."
Mental Illness"I'm not making justifications for that but there's a cause for those," she added. "You don't just have a grand mal seizure."
She also suggests her daughter may have suffered from a brain tumor or post-partum schizophrenia.
Dr. Phil prompts her to consider that, perhaps "these are the behaviors of an unconscionable psychopath," and at the end of the show offered his diagnosis to the audience. "As a mental health professional, I'm skeptical. I have not seen any evidence that Casey suffered from post-partum schizophrenia."
He also said of Cindy: "I feel this mother is desperately reaching for any reason to excuse her daughter for her role in this tragedy."
Part two of the interview airs Wednesday, but in the meantime, tell us:
For more on Casey Anthony's true-crime drama, based on PEOPLE's unparalleled access at key moments of the case, buy PEOPLE's book Outrage, available now at people.com/caseyanthony