Some websites have explored the possibility that a silencer was used in the Blue Rock Springs Park attack on Michael Mageau and Darlene Ferrin on July 4th 1969, while others argue the contrary, resulting in much debate on many Zodiac Killer forums. Nobody knows for sure, however, here we will be experimenting with the idea that indeed a silencer was used in the commission of the Blue Rock Springs attack, with an argument presented that a silencer or modified compressor was either used or carried during all four attacks attributed to the Zodiac Killer over his deadly ten-month reign. We will begin the analysis at the location of his second crime in the parking lot at Blue Rock Springs just after midnight, as the July 4th 1969 celebrations were slowly ebbing away.

July 4th (or Independence Day) is a federal holiday commemorating the independence secured from Great Britain on July 4th 1776, which is celebrated annually with fireworks, parades, family events and such like. But for one person the festival of goodwill was clearly of no concern, as he raised his 9mm Luger to the open passenger side window of Darlene Ferrin's brown Corvair - and without uttering a word - unleashed a volley of gunshots into both victims. The perpetrator then retreated back to his vehicle, only to realize that at least one of his victims may still be alive, so returned and fired off a further four rounds at the defenseless young couple. In just under forty minutes the relatively quiet neighboring towns of Vallejo and Benicia were about to receive a rude awakening, as the Zodiac Killer made contact for the first time in a payphone call that police dispatcher Nancy Slover was never to forget. 

In the police report by the Vallejo Police Department, Michael Mageau stated that as the assailant approached his passenger side door he reached for his wallet, believing the person to be a policeman. He was in the process of doing this when he heard a muffled sound and felt a pain in his back and neck area. He then heard further muffled sounds, that he interpreted as a gun with a silencer on, before the killer returned a second time and fired a couple more shots into Mageau as he attempted to cower on the back seat of the Corvair. Michael Mageau clearly states that all the shots he heard that night were muffled - again sounding as if a silencer had been employed. He did not state that the first shot was really loud and the remaining shots were muffled. If a silencer had not been employed, then clearly the first deafening shot at such close range would have understandably impaired his hearing to any subsequent shots fired off by the perpetrator that night. Michael Mageau appeared to imply that all the shots were muffled. This interview was conducted at the intensive care unit of the Kaiser Hospital on July 6th 1969, being one of Michael Mageau's earliest recollections.   

This was a life changing event for Michael Mageau, as was the phone call to police dispatcher Nancy Slover. She claimed right up to her death that the voice she heard over the phone that night is something she was never likely to forget. Some of Michael Mageau's memories of the night have altered over intervening years, but it is proposed here, that if he said two days after the attack that all the shots were muffled, then this would be the most reliable testimony he was ever likely to give. As your ear enters into trauma after the first shot, it must make the subsequent shots audibly different from the original. This, however, is a distinction Michael Mageau never made, simply stating "all the shots were muffled".

George Bryant resided in a caretakers house near the Blue Rock Springs parking lot, from where he heard the events unfold that night from approximately 800 feet away, describing the following sequence of noises. He stated that he heard "one gunshot", then a moment later "another gunshot", then after a further gap the sound of "rapid gunfire". This sequence of events markedly differed with the chain of events described by Michael Mageau, He recalled how "a white man drove up in a car, got out and walked up to their car, shined a flashlight inside and started shooting". The man then left for a brief time, before returning and firing off four more rounds. It is without doubt that Michael Mageau was under unfathomable stress that night and may have been understandably confused about the exact sequence of events that transpired, whereas, from the relative calm of his occupancy 800 feet away, George Bryant was able to give a much more reasoned and accurate account of events. He was also able to discern the difference between firecrackers being let off that night and the sound of gunfire, which he assuredly claimed were much louder. But could he?

In Corpus Christi, the two holiday dates of January 1st 2012 and July 4th 2012 were analyzed, when fireworks were most prevalent. Of the 625 emergency 911 calls received that year concerning gunshots fired, 379 were reported on these two dates alone, suggesting a significant proportion of the general public mistook fireworks for gunshots. The following video demonstrates the sound of firecrackers and gunshots, indicating that over as little as 30 yards the sounds become more indistinguishable. The greater the distance, the harder they are to tell apart. George Bryant was 800 feet from the parking lot of Blue Rock Springs. They become even harder to tell apart from within the confines of a building.
https://www.youtube.com/watch?v=oYqPAkCZfiI

We also do not know where all the sounds heard by George Bryant that night came from. Were they from Blue Rock Springs parking lot, Columbus Parkway, directly above his house or elsewhere? Without being able to determine the distance of each sound, it is impossible to determine their volume at source. So, the fact he heard some sounds louder than others is no proof of gunshots - only a perceived notion of gunshots from his standpoint.

The Zodiac Killer claimed to use a pencil flashlight to aid his aim during the Lake Herman Road double murder of David Faraday and Betty Lou Jensen on December 20th 1968, so appeared adept at modifying his weapon to suit his purpose. He also gave us a detailed description of his bomb making plans in the Bus Bomb letter on November 9th 1969 and April 20th 1970 communication, so it is actually no great leap of faith to believe that he was able to create a fully functioning homemade suppressor attachment for his gun also - or possibly own the real thing.

David Faraday and Betty Lou Jensen were mercilessly gunned down in a lonely turnout on Lake Herman Road in Benicia on December 20th 1969. David Faraday was shot once behind the left ear and Betty Lou Jensen was struck five times in her back as she fled for her life across the gravel turnout, obviously in a desperate bid for freedom. However, she managed just 33 feet from the rear of the Rambler, before collapsing backwards onto the turnout floor. At least ten shots had been fired that fateful night, testinony to which lay the strewn cartridge casings on the gravel turnout. 

Lake Herman Road traveled through undulating hills and trees as it meandered from Benicia to Vallejo in near total darkness. On the night in question it was also extremely cold, just 22 degrees Fahrenheit with the ground frozen under foot.

The sound of gunfire can travel for several miles, depending on the type of weapon, air temperature, humidity, the surrounding terrain, etc. The sound of a bullet being ejected will travel further in cold air, which has a greater density than warm air, however, Lake Herman Road was (as Zodiac stated), surrounded by high hills and trees which would help to contain any localized noise. Regardless of this, we have to consider it was about 11:15 pm at night, with local residences scattered along Lake Herman Road. Why would the Zodiac Killer attract unwanted attention to himself when his exit strategies are limited? There is one main exit road to the west and limited choices to the east. To travel eastbound and exit Lake Herman Road would take approximately 2-3 minutes, whereas westbound would take marginally longer, at around 4 minutes. Any respondents to the sound of the gunfire could conceivably have passed him as he fled the scene of crime. An unnecessary risk and one he needed never take.

James Owen, who passed by the scene just before the murders, mentioned no gunshots in his first statement to police on December 21st 1968, however,  three days later he stated "that he thought he heard a shot" approximately a quarter of a mile after he passed the turnout. On a quiet country road at approximately 11:15 pm at night, are we to believe the killer only waited 30 seconds after James Owen had passed before firing off numerous rounds from a .22 caliber weapon? But Owen supposedly only heard one. After James Owen passed the turnout, are we to conclude the Zodiac Killer only shot David Faraday (the shot James Owen heard), then waited a certain length of time until James Owen was out of earshot, then murdered Betty Lou Jensen? The sequence of events makes little sense from either perspective - and in all probability James Owen heard nothing. 

Then we had the murder of Paul Stine in the wealthy district of Presidio Heights on October 11th 1969. His dormant taxicab lay motionless at the corner of Washington and Cherry Streets, yet to be known that the Zodiac Killer had brought his reign of terror to the midst of San Francisco. The Zodiac Killer was witnessed by three teenagers across the street exiting the taxicab, before heading away from the crime scene north up Cherry Street. They stated they heard no gunshot. 

The Zodiac Killer would claim the murder of Paul Stine just two days later in a letter mailed to the San Francisco Chronicle, stating "I am the murderer of the taxi driver over by Washington St + Maple St last night". The three teenage  eyewitnesses (or anybody else) failed to hear any gunshots at the intersection of Washington & Cherry, as was the case at Washington & Maple. At 9:55 pm at night, why was this?

This crime had all the hallmarks of pre-planning, with the Zodiac Killer even removing a section of Paul Stine's shirt, which he mailed two days later along with the letter. But despite being a far more populated area, in which he secured a trophy from the crime scene, it was an unnecessary risk he was prepared to take. Again, imagine you were the perpetrator. Would you fire a loaded, unsilenced weapon within feet of a house, then proceed to start rummaging through the victims pockets, wipe down the inside of the cab, exit the vehicle and proceed to the exterior doors and start wiping them down, before moving off casually - or get the hell out of there? If the Zodiac Killer had used a silencer and believed no witnesses had observed him and called the police, then quite possibly he may have showed less urgency.  Which is exactly what the Zodiac Killer did. Finally, we will move to the brutal stabbings at Lake Berryessa, resulting in the murder of Cecelia Shepard on September 27th 1969.

Again, access to and from the scene of the crime along the Knoxville Road was limited. It was not a short journey back to the main arterial roads and on to Main Street in Napa, so the last thing the Zodiac Killer wanted to do was blast away with his weapon on the shores of Lake Berryessa, thereby creating the feeling of entrapment, with limited exit strategies. This is probably why the Zodiac Killer switched  from gun to a knife in the close quarter attack on Bryan Hartnell and Cecelia Shepard.

Bryan Hartnell observed the Zodiac Killer's gun up close and there was no suggestion of a silencer. But this does not necessarily mean he was not carrying one. However, on this occasion his knife would seve as the perfect silencer. The Zodiac Killer first presented his gun to the young couple - and although the ordeal was undoubtedly terrifying - there may have been little reason to suspect anything other than robbery as a motive at this point. The time was approximately 6:15 pm in the evening and it was still light. There were other people in the vicinity (although not many), and the thought that the assailant would start firing away with restricted exit points seemed unlikely. Unbeknownst to the couple, the assailant possessed a silent weapon, which had they seen from the outset, greater danger may have been inferred. The knife, from the perspective of the Zodiac Killer, was the perfect choice. 
The Zodiac Killer may not have used a silencer in any of the crimes, but there is one question you have to ask yourself. If you were the Zodiac Killer, hell bent on creating a legacy of evil and considering the locations he chose, would you have used a silencer?

Paul Stine arrived for work on October 11th 1969 at 8.45 pm, having taken one fare from Pier 64 to the Air Terminal, before the ill fated decision to pick up his murderer close to the corner of Mason and Geary Street in the theater district of San Francisco. In a little over ten minutes he lay dead from a single gunshot to the anterior of his right ear, discovered slumped across the passenger side of the front seating. Three young witnesses across the street from a nearby residence recalled seeing a man in the front of the taxicab, the victim slumped over his lap, wiping down various sections of the interior and leaning over towards the driver side compartment. He then exited the taxicab and proceeded to the driver side door, that faced into the street, which he then wiped down, presumably to remove fingerprints. However, if this were the order of events, how did the murderer ever place himself into contact with the driver side door or panel of Paul Stine's taxicab.  The only reason to have touched the driver side door of the taxicab or its adjoining panel, was that he either leaned on it after he summoned the taxicab at the Mason and Geary intersection and spoke to Paul Stine, or he actually opened the driver side door to gain access to the vehicle. The first option seems unlikely, knowing that in a matter of minutes he is about to put a gun to the head of the taxicab driver and brutally execute him, so leaving fingerprints in advance on a door, he later has to waste time removing after the murder seems unnecessary.    

But lets go back to basics and examine the evidence as we actually know it, beginning with the Zodiac Killer letter mailed to the San Francisco Chronicle on October 13th 1969, in which he states ''I am the murderer of the taxi driver over by Washington St + Maple St last night'. Why does the killer mention Washington and Maple when the taxicab was found at Washington and Cherry. He clearly had knowledge of his location as he refers to both street names, and although the Zodiac Killer could not be taken at face value, there was nothing to be gained by claiming the murder at the wrong location, and for this reason alone we have to conclude that this is probably where Paul Stine was shot. There are three key pieces of reasoning that point us towards this hypothesis, namely that the three teenage eyewitnesses from the house overlooking the intersection of Washington and Cherry Street did not recall hearing any gunshot at this location, albeit, this may have resulted from the possibility that a suppressor was employed in the commission of the crime, or from the close contact wound that muffled the sound. Secondly, the blood pattern on the Paul Stine's shirt that tells its own story. 

And finally the killer was seen wiping down the driver side door, one assumes to remove any incriminating fingerprints. These three key ingredients may tell us the true story of the events that unfolded on that fateful night back on October 11th 1969, and one that differs substantially from the widely believed order of events.
As the taxicab approached the corner of Washington and Maple Street, Paul Stine did not place the car into park, knowing he was on a 'run through' to his original fare at 500 9th Avenue, radioed to him by Yellow Cab dispatcher Leroy Sweet, when suddenly the killer raised the gun into Paul Stine's eye-line. It clearly states on the autopsy report there were dark marks on the dorsal side of the Paul Stine's left hand, that may suggest that as Paul Stine reacted to move away from the danger, his left hand was raised in order to deflect the gun away at the instant of firing, resulting in dark stippling marks. During this melee, Paul Stine inadvertently broke contact with the brake pedal, causing the taxicab to motion forward out of control, possibly towards the sidewalk. Wanting to avoid an imminent crash and alerting the entire neighborhood, the Zodiac Killer either lunges forward to grasp the steering wheel and clambers over to the front of the taxicab to regain control of the vehicle, or exits the left rear passenger door and enters the driver side door. He then has to push his body weight against Paul Stine (who remains in a sitting position), against the driver side door to access the vehicle controls and thereby coast the taxicab to the corner of Washington and Cherry Street where he finally parks up.

The blood pattern on Paul Stine's shirt indicates that for a measurable time period his body must have been in an upright position, to display the pattern exhibited by the photograph on the left. If Paul Stine had been shot at Washington and Cherry Street and had immediately slumped over to rest on the front passenger side seat, shown in the crime scene photographs, the blood pattern would be altogether different. The shirt displays blood from a head wound, falling with gravity, downwards and around the chest, predominating on the right side, as he was shot behind the right ear. The idea Paul Stine was pushed against the left driver side door when the Zodiac Killer commandeered the vehicle, is also exhibited, as the angle of body tilt would lead to blood flow on this side also, albeit marginally less in the pattern displayed. This concept was further analyzed in a previous    

article, suggesting that the Zodiac Killer for this reason walked on the north side of Jackson Street, so that his predominantly blooded left side faced away from the roadside and any oncoming traffic and police vehicles. If his left side had not been covered in blood, walking on this side of the street, in closer proximity to oncoming headlights would have seemed the less preferred option.  See http://www.zodiacciphers.com/zodiac-news/the-silent-murder-at-presidio-heights.
However, we have a problem;  If the Zodiac Killer had jumped from the back seats to the front and gained control of the taxicab by leaning against Paul Stine, at the end of the journey, it would not have necessitated the murderer walking from the front right passenger side door to wipe down the exterior of the driver side door and panel. The fact he did indeed perform this action suggests at the very least he must have deposited fingerprints on it at an earlier time. As explained earlier, if he had hailed the taxicab by approaching the driver side door at Mason and Geary Streets with murder on his mind, the last thing he would have done was to touch the driver side door handle, an action that necessitates the later removal of fingerprints. If the Zodiac Killer had remained in the rear of the taxicab for the entire journey, why on earth after killing Paul Stine, would he be wiping down the interior driver side compartment of the taxicab, after all, there was no reason to have ever touched these areas. If he had opened the right front passenger side door with the express intention of removing a piece of Paul Stine's shirt, the only three things he needed to touch would have been the rear right door handles, the front exterior passenger door handle and Paul Stine's shirt, nothing else. The wiping down of the interior of the cab and exterior driver side door makes little sense, unless he touched it.

This suggests the Zodiac Killer must have touched the driver side door handle other than at Mason and Geary Streets and Washington and Cherry Streets. The only remaining option being the Washington and Maple Street intersection, where he claimed to have committed the murder all along. However, this would debunk the idea, the killer clambered from the back seats to the front seats. The only possible scenario left that makes any sense, is that when the vehicle ran out of control, he quickly exited the vehicle on the roadside, opened the driver side door of the taxicab with his left hand, deposited blooded right fingerprints on the door panel as he braced himself against the moving vehicle, and stepped over the lifeless body of Paul Stine touching the driver side compartment as he did so. 

The most credible course of events, is that after shooting Paul Stine the vehicle motions forward. The Zodiac Killer reacts instantly by exiting the left rear door, opens the driver side door, grabs the steering wheel, then steps over the motionless Paul Stine, closes the door and uses his left foot to access the taxicab pedals and coasts the vehicle one block further on, where he ultimately disappears north along Cherry Street. This covers all of the known facts, the blood pattern on the shirt, the necessity to wipe down the driver side door handle, the necessity to wipe down the interior driver side of the cab and his decision to walk on the north side of Jackson Street, in the full glare of police headlights heading towards the crime scene at the Washington and Cherry Street intersection 
Donald Fouke, a police officer responding that night, recalled a man walking with a shuffling lope along the north sidewalk of Jackson Street, heading towards the intersection of Jackson and Maple. If, as hypothesized, the Zodiac Killer exited the moving taxicab at Washington and Maple, is it possible he injured his ankle or leg in the process, resulting in the 'shuffling lope' described by Donald Fouke from his patrol car. The direction of the Zodiac Killer also makes sense, in that, if he had killed Paul Stine at Washington and Maple without any mishaps, he would likely have been walking north along Maple Street towards the Jackson and Maple intersection, the direction he was ultimately heading when spotted by Donald Fouke, only he had traveled one extra block unnecessarily. 
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http://www.zodiackillerfacts.com/blog/mysteryquest-paul-holes-and-the-murder-of-paul-stine