Pat claims his father, John, is delusional and violent, and responds to seemingly benign events with what John interprets as threats. One example that Pat points to is John’s reaction to a letter that Pat’s 7-year-old son wrote to his beloved grandfather thanking him for birthday money.

WATCH: Son Calls Father ‘Paranoid,’ Delusional, Dad Says Son Is Violent And Threatening

Part of the letter from Pat’s son to John read:

Dear Grandma Bev and Grandpa John,
Thank you for the card and money.
Thank you, love you, Carter

“My wife and I became alarmed when my dad took my son’s handwritten thank you letter as a threat on his life,” Pat says.

According to Pat, John responded with a three-page letter accusing Pat and Sarah of sending a “murder” letter.

In the video above, Dr. Phil reviews the letter that John received from his grandson. And, John explains why he believes it’s a threat to him and his wife.

Later, Dr. Phil asks John, “Is it possible that’s not a coded death threat?”

“Oh, it’s entirely possible,” he says.

Dr. Phil attempts to bridge the gap between father and son and bring this whole family together on Monday’s episode. Watch more here.