In the November 9th 1969 'Bus Bomb' letter the Zodiac Killer was clearly agitated by the response he received after mailing the Paul Stine letter on October 13th. In it he stated "This is the Zodiac speaking up to the end of Oct I have killed 7 people. I have grown rather angry with the police for their telling lies about me. So I shall change the way the collecting of slaves. I shall no longer announce to anyone. When I committ my murders, they shall look like routine robberies, killings of anger, + a few fake accidents, etc." The newspaper article that upset him featured Chief of Police Martin Lee, who stated in the San Francisco Chronicle article on October 18th 1969 entitled 'Zodiac Called a Clumsy Criminal,' that Zodiac possibly left his fingerprints on the taxicab, allowed himself to be spotted by three teenagers, and failed to kill all his victims. He went on say "His boast of being in the area we were searching is a lie. We had the whole area flooded with lights. We had seven police dogs and a large number of patrolmen searching the area tree by tree and bush by bush. The dogs are the best in the country. A mouse couldn't have escaped our attention."
The question was; had the Zodiac already attempted or carried out a crime after the October 18th 1969 article that was designed to look accidental or natural, but had possibly failed. After all, his victim count remained at seven by the end of October, which he corroborated in the Dripping Pen Card on November 8th. To do so, we would have to look at attempted crimes, claimed by the 'Zodiac Killer' between October 18th and November 8th, in a relevant location.
As seen on the left, a Salesian High School teacher, Daniel Williams had his house broken into, but nothing was taken. A man claiming to be the Zodiac Killer made several threatening phone calls beginning on October 23rd 1969, culminating with the caller saying "You're the dead duck" on November 2nd 1969. Later that day Williams took a drink from the refrigerator, but fortunately spat it out after noticing a metallic taste. The drink contained enough arsenic to kill.
This in all likelihood is not the Zodiac Killer, however the targeting of a school teacher is interesting, bearing in mind a Salinas High School teacher, Donald Harden cracked his first cipher, and his 'Dripping Pen' card and second cipher was to arrive in just six days. It could also be argued that this attempted murder, had it been successful, may have looked 'accidental', as the Zodiac would state in the 'Bus Bomb' letter.
Daniel Williams residence was situated at 1234 Bush Street, Martinez, only 9 miles from the location of Zodiac's first crime at Lake Herman Road.
The mystery man during one of his calls talked of "killing the lady in the blue house," but as of yet the meaning behind this utterance is undetermined. 
Bearing in mind the October 22nd 1969 Jim Dunbar radio show, in which Zodiac was supposed to call in, it is hardly surprising we may get a crank call by somebody claiming to be Zodiac beginning on October 23rd 1969. The only difference here, was it appeared the caller was prepared to back up his threat with action. The original caller to the Oakland Police Department at 2.00 am on October 22nd 1969 may however not be the same person as the hoaxer, who ultimately called the Jim Dunbar show and spoke to Melvin Belli.

​The phrase 'dead duck' may originate from "Never waste powder on a dead duck," first recorded in 1829. Bearing in mind the use of arsenic powder, an ironic choice of words. 

On October 22nd 1969 the Oakland Police Department took a call in the early morning hours from somebody claiming to be the Zodiac, requesting that either Melvin Belli or Francis Lee Bailey, high profile lawyers at the time, appear on a chat show hosted by Jim Dunbar later that day. Melvin Belli agreed to appear on the show to which a man would eventually contact via telephone, claiming not only his name was 'Sam', but also by inference that he was the infamous Zodiac Killer.
Three people had heard the voice of the Zodiac Killer, Bryan Hartnell who survived the brutal attack in Napa and two police dispatchers Nancy Slover and Dave Slaight, who all categorically stated that the man called 'Sam', who rang into the Jim Dunbar show was not the same voice they had recalled from the Blue Rock Springs and Lake Berryessa attacks and therefore not the Zodiac. It was believed that Eric Weil, a mental patient was responsible for the hoax call to the Jim Dunbar show in the October of 1969. It is unknown whether the original caller to the Oakland Police Department was the real killer.  
However, just three and a half months later on February 5th 1970 a second phone call would arrive during an on air interview by Jim Dunbar with a movie producer. The caller claimed to be the Zodiac Killer.  

SAN FRANCISCO (UP!)- A man claiming to be the Zodiac killer of five persons held another on-the-air conversation today with television personality Jim Dunbar. Two police inspectors closeted themselves with Dunbar at station KGOTV immediately after the one-sided conversation, which consisted mainly of Dunbar asking questions and repealing fragments of answers. “When headaches come on, you kill to get relief?” Dunbar asked at one point. “What other stuff you been on besides glue?” Last October 23, Dunbar and attorney Melvin Belli, a guest on his early morning talk show, held a bizarre conversation with a man who said he was Zodiac. Belli set a meeting with the man, who did not show up. Today's call interrupted an interview by Dunbar with a movie producer.
Police believe Zodiac is responsible for five killings in Northern California in the last 13 months. In a series of taunting cryptograms and letters to newspapers and police he has boasted of killing seven and threatened to kill more. Dunbar’s side of the conversation was recorded but not the other voice. The station said something had gone wrong with the monitor on the caller’s voice. The conversation ran, in part, like this: "What other stuff you been on besides glue? Oh, gas? flow do you get? Oh. Do you still have parts of the shirt you sent the newspaper? Oh. . , . Did the victim make a move on you? In other words, you thought he was going to move? .... Did you have the 9 mm gun? Oh, three guns. What, four guns? How could you conceal four guns?
‘‘When headaches come on, you kill to get relief? . . . Chief evil is what ? . . . Sonny Barger of Hell’s Angels?. Meridith Hunter—you are going to do it yourself to bring justice on the Meridith Hunter murderer? Oh. . . Were you anywhere near Altamont for the rock concert? Oh, you knew it was a hoax? . . . You weren’t there?. . . . “You hate Yellow Cabs? . . . Is that why you killed Paul Stine? . . . You want Belli to represent you? . . . You want life in prison, not death?. m m Why Friday 13th? Is that a bad day? ... You say you’re a tranquility smoker? ... Oh, for 10 years? How can you say that when you’re only 18? . . . What usually brings your headache on? You go without sleep? Months? .. . Are you gassed now? . . . Why do you mix booze with drugs? "Why don’t we get together before Friday 13th? ... You say southwest corner of the Tonga Room? You have a girl? Oh, two. Pretty young, you say, 21 and 24? . . . Tell me one thing you told Belli that I don't know, or wrote to him that nobody else knows. I won't repeat it.”

The Tonga Room is a tiki bar established in 1945 in the Fairmont Hotel, Fairmont, San Francisco, 950 Mason St, San Francisco. The Tonga Room is 10 minute walk from the intersection of Mason and Geary Streets.