Mel Gibson's Dad Hutton Gibson -- Allegations of Elder Abuse

Mel Gibson's father -- who filed for divorce Monday -- believes his wife has been abusing him, and Mel has jumped to his dad's aid ... TMZ has learned.

We're told Mel and his family have been tending to 93-year-old Hutton Gibson, who is seriously ill with a panoply of ailments. Hutton is taking a slew of medications for his conditions, but we're told his wife, Teddy Joye (who is in her 70's) believes her husband's family is prolonging his suffering and wants to discontinue all medicines to accelerate his death. She also believes that's what Hutton wants.

We're told Mel has taken the lead to ensure his dad is getting his meds, and believes Joye is guilty of elder abuse by her conduct. Sources say Mel wants Joye out of his dad's house -- stat.

As we first reported, Hutton personally filed for divorce and even signed the divorce docs in shaky handwriting.

We're also told Joye is going to fight it out with Mel -- possibly in court.