According to The Washington Post, "no cause of death was reported." Really? No cause of death? Hmmm, do you think he may have died because he was 97-years-old?!
When a person who is three years away from being 100 passes away, the only time the cause of death should be reported is if it's something unexpected like skydiving or stingray piercing or erotic asphyxiation. Otherwise, we'll just assume it's old age.
Karl Malden was married for 70 years. As Alan King would say, "He was survived by his wife!"