September, 1966
Doctor Zodiac appears in World's Finest Comic #160
Doctor Zodiac hijacks an aircraft, ransoms the passengers, then escapes by parachute:
1957 -
Dan Cooper comics
"......storylines seemingly match aspects of the D. B. Cooper case, including jumping out of a plane with a parachute, as well as a ransom being delivered in a knapsack." - https://en.wikipedia.org/wiki/Dan_Cooper_(comics)
December, 1969
Zodiac Killer sends bus bomb letter. http://www.zodiacciphers.com/bus-bomb-letter.html
Thanksgiving Eve, 1971
D.B. Cooper Skyjacking
Letters sent to newspapers double stamped with cutout messages similar to Zodiac correspondence- https://en.wikipedia.org/wiki/D._B._Cooper
October 27, 1970
Zodiac Killer sends Halloween Card. Writes on back: "BY KNIFE - BY GUN - BY ROPE - BY FIRE"
Skeleton in card has Red Mask
Writes on side "You are Doomed"
1952
Tim Holt #30 " Redmask Meets Lady Doom and the Death Wheel"
Death Wheel reads: "BY KNIFE - BY GUN - BY ROPE - BY FIRE"