Zodiac k**er - "This code will tell you where the bomb is set", 13th Zodiac Letter lyrics

This is the Zodiac speaking. I have become very upset with the people of San Fran Bay Area. They have not complied with my wishes for them to wear some nice [Zodiac logo] bu*tons. I promised to punish them if they did not comply, by anilating a full School Buss. But now school is out for the summer, so I punished them in another way. I shot a man sitting in a parked car with a .38. [Zodiac logo] - 12 SFPD-0 The map coupled with this code will tell you where the bomb is set. You have untill next Fall to dig it up. [Zodiac logo] (cipher) (on map) 0 is to be set to Mag. N. 3 6 9