In the following attack at Lake Berryessa, Bryan Hartnell never saw the suspect's face at all, so we only have a recollection of "voice concept", which in not particularly ideal. A 2010 study from the Journal of Social, Evolutionary, and Cultural Psychology found that when people try to guess the age of male speakers over the age of 35, or female speakers over age 55, they’re at least 10 years off on average. They also tend to underestimate the age of speakers as they get older. Additonally, Bryan Hartnell stated to Napa detectives regarding the voice on the Jim Dunbar Show and featured in the San Francisco Chronicle on October 24th 1969, that "he remembers Zodiac's voice as much older and deeper than the one heard in the series of telephone calls to KGO-TV". The next line in the newspaper article added that his opinion was backed up by Napa police Patrolman Dave Slaight and Vallejo police clerk Nancy Slover. The caller to the Jim Dunbar Show was Eric Weill, who was aged 29 at the time. This means that Bryan Hartnell described the Zodiac's voice as much older and deeper than a 29-year-old, and is in direct conflict to his earlier estimate of 20 to 30 years. This clearly demonstrates the inaccuracy of determining age through voice concept. The only attack where the Zodiac Killer's face was seen for any reasonable length of time was on October 11th 1969. At Presidio Heights there were three sets of eyewitnesses who saw the Zodiac Killer from the taxicab to the park - and all gave the same age. The three teenagers described a man in his early forties in the police report on October 12th 1969, Officer Donald Fouke described the man as 35-45 (therefore a median age of 40) and the Julius Kahn playground eyewitnesses described the man running into the park as about 40. Three sets of eyewitnesses pinpointing the Zodiac Killer as 40 years of age or slightly above, within a five minute window.
These three sets of eyewitnesses gave a very similar description, as follows:
The three teenagers described the suspect to the police dispatcher as a "WMA, in his early forties, 5'8'', heavy build, reddish-blond "crew-cut" hair, wearing eyeglasses, dark brown trousers, dark (navy blue or black) "Parka" jacket, dark shoes". Donald Fouke described the suspect as a "WMA, 35-45 yrs, about 5'10", 180-200 lbs, medium heavy build, barrel chested, medium complexion, light colored hair possibly graying in rear, crew cut, wearing glasses. Dressed in dark blue waist length zipper type jacket (navy or royal blue). Brown wool pants". The eyewitnesses at Julius Kahn playground (Spruce Street) described the suspect in the San Francisco Chronicle article on October 12th 1969 as "white, about 40, 170 pounds, a blond crewcut, wearing glasses. He was wearing dark shoes, dark grey trousers and jacket". The only minor difference being brown trousers described as dark grey. Every other detail matched up in this five minute window.
The three teenagers never described the suspect as 25-30 years - only the October 13th 1969 police sketch did. Their account was comprehensively detailed in the police report countersigned by Officer Armond Pelissetti on October 12th 1969. Their viewing of the suspect "last seen walking north on Cherry Street, from Washington Street" was the only eyewitness testimony in the police report, and therefore the suspect description on page 2 could only have been derived from them. It stated the man was in his early forties. It couldn't have been from the other two sets of eyewitnesses because the police report clearly states that the suspect was "last seen walking north on Cherry Street, from Washington Street". The other eyewitnesses viewed the suspect after Cherry Street.
The three teenagers sat down with a sketch artist who interpreted their description of the man - and it's extremely likely that because the sketch was interpreted and drawn looking younger, the police attributed the age range of 25-30 years to it - likely believing this was the correct course of action based on the appearance of the sketch. In other words, the contradiction of the three teenagers early forties description in the police report to the appearance of the sketch, likely played a part in the revision of the age range placed on the wanted poster. However, it is apparent that the three teenagers were not happy with the first sketch, forcing the police to create an amended sketch more in line with their original early forties description. The police then released the amended sketch on October 18th 1969 with a compromise age range of 35-45 years, which allowed for any slight error either way. To believe the three teenagers described the suspect as in his "early forties" in the police report on October 12th 1969, but one day later completely backpedalled to 25-30, defies logic. Especially when you consider the sketch was amended to 35-45 on October 18th 1969 with their help. Obviously dissatisfied with how the first sketch was presented.
Here is an excerpt by Donn Devine: "But just how long is a generation? Don’t we all know as a matter of common knowledge that it generally averages about 25 years from the birth of a parent to the birth of a child, even though it varies case by case? And wasn’t it closer to 20 years in earlier times when humans mated younger and life expectancies were shorter? Where did those numbers come from? Several recent studies by a sociologist-demographer and groups of population geneticists and biological anthropologists show that male-line generations, from father to son, are always longer on average than female-line generations, from mother to daughter. They show, too, that both are longer than the 25-year interval that conventional wisdom has assigned to a generation. The male generation is at least a third longer, the female generation is longer by perhaps half that amount".
Most people affix around 20-25 years to a generation, so if we take the average of the four victim's ages from the first two attacks, we would arrive at 19 years. Add the generational divide of 20-25 years and we have a suspect between 39-44 years of age - a man in his early forties or about 40. We know the attack at Presidio Heights was a Zodiac crime because of the blooded shirt piece of taxicab driver Paul Stine being mailed to the San Francisco Chronicle. Therefore, these three sets of eyewitnesses in a time window of just five minutes, all describing a man about 40 years of age, should carry great value. But does this argument have any sway with the long-held convictions of people regarding suspects in the Zodiac case, or will no amount of eyewitness testimony alter the lens through which they view the Zodiac case? This analysis has been performed in an objective fashion because I have no allegiance to any suspect whatsoever. However, somebody approaching this topic with a subjective analysis, looking at this case through the lens of their favorite suspect, will inevitably cherry-pick which eyewitnesses to believe or dismiss (or give credence to) based on what is convenient to their suspect's age. If people are going to use the first police sketch on October 13th 1969 with an age range of 25-30 to bolster the case for their young suspect, then they should also accept the rest of the material present on this sketch, such as the killer sat in the front seat, tells the driver the destination as the Washington & Laurel area or area near Park or Presidio, and upon reaching destination, orders driver to continue on at gunpoint. This of course is all fiction, yet the 25-30 age range is routinely quoted as the suspect's age, despite the three teenagers never once stating this to be the case.
In 1969, the ages of the most widely touted suspects were: Theodore Kaczynski (27), Bruce Davis (27), Gareth Penn (28), Ross Sullivan (28), Richard Gaikowski (33), Arthur Leigh Allen (35), Richard Marshall (41), Lawrence Kane (45) and Kjell Qvale (50). Based on the eyewitness testimony at Presidio Heights, only two candidates fit the age description of the Zodiac Killer and these are poor suspects at best. The farther we travel to either end of the suspect age-scale spectrum, the weaker the argument becomes for these men to be the infamous Zodiac Killer. People often defy their years, but the argument still stands.
We have multiple eyewitnesses at Presidio Heights, all of whom were able to give fairly detailed descriptions of a killer emerging from the taxicab, heading up Cherry Street, turning into Jackson Street, before seeking refuge in the Presidio Park just after 10:00 pm. These are without doubt the best eyewitnesses we have in the Zodiac case.