In S01E23, jane discovered that Sheriff Hardy (Dumar) was a friend of Red John and his father was an accomplice of Red John , and was in the farm on 90's.
Sheriff Hardy (Dumar) was born on 16 septembre 1978, so now he is 35 years old.
we can estimate his father's age between: 55 and 65 years.
Red john is a friend with the father and the sometime with the son.

  Sheriff Thomas mccalister is 58 years old.
  Robert Kirkland is 44 years old.
  Raymond haffner is 46 years old
  Gale bertram is 51 years old.