November 9th.1969 + Death Machine letter sent to Sanfrancisco Chronicle~
A portion of the letter talks about the disguise:
"The police shall never catch me, because I have been too clever for them.
1 I look like the description passed out only when I do my thing, the rest of
the time I look entirle different. I shall not tell you what my descise
consists of when I kill"
According to the Zodiacs own words, the Sketch had a disguise. I guess that meant that he wore glasses only when he killed. This is a 'Looking Glass' clue.

November 29th 1966, a letter attributed to the Zodiac and possibly speaking of the 1966 crime of Cherry Jo Bates,Age 17. Cherry did not have a red dress on:
Crime:http://www.zodiackiller.com/Bates.html
A potion of the letter found here ~ http://en.wikisource.org/wiki/Zodiac_Killer_letters
"BUT ONLY ONE THING WAS ON MY MIND. MAKING HER PAY FOR ALL THE BRUSH OFFS THAT SHE HAD GIVEN ME DURING THE YEARS PRIOR."
This sounds like the Zodiac was 17 when he first killed(if this is indeed the first year he killed. Lets not forget the 1963 murder of the 5 year-old girl Dorene, which would then, if attributed to Zodiac, put the age he first killed at 14.
Zodiac plays on the #14 in his halloween card. 14 in alphabet is AD and could mean After Death since the Zodiac consistently spoke of the after life.

I do not think the Zodiac wore glasses when he was not killing. I also think he is alive, well, and 63 years of age.