The menacing postcard was directed toward Dr. Edward Adams in Orinda, CA, stating
"The Zodiac is going to change the way of committing murders. I shall announce when I shall commit my murders, The Adamses are Next you taught me to Mean it.
ADAMS YOU ARE NEXT. ZODIAC."
Whether the '13 Hole' postcard was a genuine Zodiac communication and this was a copycat, both were crafted by the hands of a hoaxer, or both were authentic Zodiac material, is a matter of opinion.
The Zodiac Killer Site forum has covered this topic extensively, so to read more about this postcard, please visit the link above. Any opinions regarding the 'You are next' and '13 Hole' postcards would be welcome.
I have cleaned and enhanced the postcard for better viewing (see below).