Maybe this could also have been the incident which prompted the letter. This happened on the 03 Jan 2001.

COTTER, Brian Edward — Age 18, was struck down in a tragic accident on January 3, 2001. He will be eternally missed and adored by his loving father and mother, Neil and Mary Cotter; his sisters Colleen and Megan and brother Sean; loving grandson of Margaret & James Cotter in Ireland and the late Edward & Catherine Coleman. Also survived by many aunts, uncles, cousins and friends, he was a senior at St. Ignatius College Preparatory High School where he was a forward on the soccer team. Brian touched the hearts of everyone who knew him and was a bright star in our lives. Friends and family are invited to visit Sunday after 6:00 p.m. at St. Ignatius Church, 650 Parker Street, S.F. where a Vigil Service will be held at 7:30 p.m. A Funeral Mass will be celebrated Monday at 10:00 a.m. at St. Ignatius Church.

Another great find with respect to the 2001 card Cragle. The more information we have, the more chance we have to understand why this story was so pertinent to the Zodiac or the hoaxer.

If the letter was about a releative of his that was killed.
Brian edward Cotter the 18 year old who was killed has a very similar nose to the zodiac sketch.

Okay if anybody is interested I think I have tracked down the address of Ouyang. 2206 Irving st, SF.

Yes, I’m interested – good find.

Another interesting thing of note is that the Cotter family were living in Millbrae at the time of Brian’s accident. The previous year they lived at 2142 32D Av, SF which is again in the Sunset district of SF.

Seems like a good idea to search for Cotters who could match Zodiac geographically and age wise.

Here you go Sandy, a little comparison.

2001 has wiggly "l"s, capital "N"s in the middle of words, double-story lower case "a"s, hooks on the "S"s, weird "t"s, horizontal lines on the "F"s extend to the left…."901" is clearly different, too.