"The man who told police that my car was brown was a negro about 40-45 rather shabbly dressed. I was in this phone booth having some fun with the Vallejo cop when he was walking by. When I hung the phone up the damn thing began to ring & that drew his attention to me + my car." Debut of Zodiac Letter: August 4th 1969.
At 12.47 am Mrs Johnson PT&T operator called. The above call was traced to a coin operated telephone at Joe's Union, Tuolumne and Springs Road. The call was traced by Betty Main, whose supervisor would not allow her to give a statement at this time.
The Zodiac Killer called at 12.40 am and the call was traced inside of seven minutes, which is not possible with the technology of 1969. A caller had to be on the line a minimum of 15 minutes for a call to be traced. Although not completely accurate, this was referenced in the Zodiac (2007) movie, featuring a clip of the Melvin Belli 'call to chat show,' when Belli was instructed "Pacific Telephone says you need to keep him on the line for 15 minutes."
It is likely the word 'traced' is being used in the loose sense of the word, and they actually 'discovered' the call was made from Springs and Tuolumne.
Michael Cole, author of Zodiac Revisited made some interesting points on the Zodiackiller.com forum:
"(1) The information from the letter is being given in direct response to a request for additional identity verification. The other information given in the same context appears to be truthful (mostly). Therefore, I believe Z is being honest in the conveyance of this information.
(2) We know that Z changed his behavior when he made his call to the Napa PD about three months later. Instead of hanging up the phone, he set it down thus avoiding the possibility of a ringback. This behavior modification is consistent with an experienced-based learning regarding the described ringback; not to mention it just sounds like good police procedure to implement a ringback under these circumstances. Therefore, I suspect the ringback did happen as described. Perhaps Nancy will provide some additional insight on this front. I've already asked the question in the other thread.
(3) We know that Mike Mageau described the car as being brown.
(4) As mentioned previously, Z's statement implies that he knows somebody told police that his car was brown. Although I don't have the reference, this clearly implies that the detail was published somewhere.
Given all of the above, I suspect that Z honestly believed that the described witness was the person who told police about his car. He apparently, quite reasonably, believed that MM could not have ascertained the color of his car. This left the witness as the most probable source. The fact that the witness was never identified seems to imply that he chose not to come forward or that he was unaware of law enforcement's desire to talk to him."
But the fact the location of the payphone was 'traced' seems to implicate third party information, in that ring-back alerted somebody to its location. However, that still leaves the question - if the negro male was interviewed, was he able to give any additional information regarding Zodiac's description, that was 'incorporated' into the police report, or did his description simply tally with Michael Mageau's and was therefore not included. Or did he simply get no viable description of the killer or his vehicle at all. Either way, as Michael Cole stated, the Zodiac Killer would not make the same mistake again in Napa on September 27th 1969.