It would take something pretty amazing to get a false positive match, imo. Like all the forces of the universe coming together at once to line up all the tiniest of details and similarities.
On a 13 marker match yes absolutely. 1 chance in 10 billion.
But no not on a mere 4 marker profile. That might match 1/10 of 1% of the population. That might not sound like a lot but that means about 300, 000 people in the US.
BOTTOM LINE there is no valid profile. Read my post below.
MODERATOR
Mike B Did a good FAQ on the Zodiac DNA.
a partial profile can only eliminate an individual as the donor of the DNA. The partial profile cannot positively identify the Zodiac because the profile is incomplete.
I don’t agree with all his conclusions but I can partially backup what Mike is saying fact wise. After a long period of presenting and discussing evidence I finally was able to convince an investigator on the original night stalker case to compare the DNA in that case with the DNA that the SFPD was claiming it had in the Zodiac case. This investigator asked the SFPD for the information to do the comparison and he was denied and told that they " did not have confidence" in the partial DNA profile that they had.
All they had was 4 markers and you need a minimum of 9 for CODIS. At one time they touted this as a likely Zodiac profile but told this investigator that a "lab person misspoke" in doing so. Which may be pure CYA.
It was Inv. Larry Montgomery of the OCDA who asked SFPD for the DNA.
MODERATOR
Always appreciate reading your DNA insights, Mike, I can certainly understand why the apparent uncertainty would be frustrating for you. I guess I’m trying to get my head around why SFPD would conduct this kind of dog and pony show of agreeing to compare a potential suspect via a DNA sample that they themselves felt was questionable. I suppose they could hope that a match would prove that it was a valid sample but it could also serve to forever rule out good suspects improperly. It would seem to me that handwriting, fingerprints and DNA should all probably be used together to try to rule anyone in or out at this point.
I recall Sandy made a post last year after she attended some event in SF. I think it was a special screening of Fincher’s Zodiac. Sandy posted that at the event a female member of SFPD stated that the department did have Zodiac DNA. I think the partial profile is a joke myself, but apparently SFPD is still publicly claiming to have faith in its partial profile.
The transcript for the 20/20 program is posted at Jake Wark’s site.
http://members.aol.com/ZArchives/primetime.htm l”> http://web.archive.org/web/200602080054 … etime.html
Here are the portions that address the DNA.
"…
DIANE SAWYER
Tonight, a promising breakthrough in the case. He left an ominous trail of letters and cryptic puzzles, signed with a chilling trademark, a name tied to the occult.
DOCTOR CYDNE HOLT, SAN FRANCISCO POLICE DEPARTMENT
I would then try to recover DNA from the cells that may have been deposited on the letter.
DIANE SAWYER
Explosive new DNA evidence, uncovered during "Primetime’s" year-long investigation reported here for the first time.
JOHN QUINONES
(Off Camera) You’re looking at the genetic identity of Zodiac. What does that feel like? ….
JOHN QUINONES
(Off Camera) Diane, he called himself Zodiac and he left behind a trail of bodies and taunting letters. Then, suddenly the murders stopped and he went silent. For the past year, "Primetime" has been digging for clues. The case has been reopened. Cutting-edge science is being used to find the true identity of the killer. And now, there’s critical new evidence which we’ll tell you about tonight. But first, we take you back to the beginning of Zodiac’s reign of terror. …
JOHN QUINONES
(Voice Over) The headlines focus on terror. The public is transfixed by the menacing threat of random murder. Yet for three decades the Zodiac, a brazen serial killer who was so careful about leaving a trail, remains at large. But today, thanks to new crime scene technology, there’s reason to believe that time may have run out on Zodiac. Somewhere, perhaps on the back of this postage stamp or in the seal of this envelope, may be microscopic clues that will now finally lead police to the killer.
DOCTOR CYDNE HOLT
We’re hoping to be able to get some genetic information about the individual or individuals that did seal these envelopes or place stamps on them.
JOHN QUINONES
(Voice Over) In the San Francisco Police Department’s state of the art DNA lab, Doctor Sydney Holt(PH) is taking up the hunt for Zodiac. Careful as he was, it’s unlikely that 33 years ago, Zodiac would worry about leaving behind a genetic trail, or that a kindergartner at the time, little Sydney Holt, would grow up to become a police scientist and come looking for him.
DOCTOR CYDNE HOLT
If there are cells on those envelopes, we will get the DNA from them and, and get an answer. …
DOCTOR CYDNE HOLT
It’s a mystery that seems to have a lot of people’s curiosity piqued. And I get asked about it with some frequency.
JOHN QUINONES
(Voice Over) After all, the identity of Zodiac is one of the most enduring unsolved mysteries. And that’s why Doctor Sydney Holt is now on the case. She begins with the remaining envelopes Zodiac mailed. More than half disappeared over the decades. First, she removes the stamps and flaps.
DOCTOR CYDNE HOLT
I would then try to recover DNA from the cells that may have been deposited on the letter when someone had licked it.
JOHN QUINONES
(Voice Over) She uses a centrifuge to separate the cells from the sticky adhesive.
DOCTOR CYDNE HOLT
The science is so sound and reproducible that if the material is on the envelope, we will detect it.
JOHN QUINONES
(Voice Over) She uses the newest DNA detection technique called Polymerase Chain Reaction, PCR for short. To produce a genetic profile, it needs just 50 human cells.
DOCTOR CYDNE HOLT
We can start with a very, very small amount of material, like you would have on the Zodiac letters, and actually make more copies of the DNA, like a little Xerox machine, and amplify the areas of the DNA that are different between different individuals.
JOHN QUINONES
(Voice Over) This is what she’s looking for, a pattern of spikes that indicates the presence of DNA. But results from two of the first three envelopes are negative.
DOCTOR SYDNEY HOLT
I can’t detect any DNA.
JOHN QUINONES
(Voice Over) The test produces only flat lines.
DOCTOR CYDNE HOLT
Disappointing. Certainly not the end.
JOHN QUINONES
(Voice Over) Not the end because there’s still work to do on that third envelope, the one Zodiac used for his menacing greeting card. Back when he-mailed it in the summer of 1969, Zodiac probably wasn’t worried about getting caught with future science. . …
JOHN QUINONES
(Voice Over) But back in 1969, profiling a serial killer is still a thing of the distant future. In fact, police at the time are stymied. A composite sketch of the killer released shortly after the cab driver murder, describes Zodiac as 35 to 45 years old, of stocky build and wearing thick-rimmed glasses, his hair, possibly, reddish-brown. And now, decades later, Doctor Cydne Holt finds what appears to be a reddish-brown hair stuck behind a stamp peeled from this letter. Could this tiny strand bear Zodiac’s DNA finger print? She examines it, but again no luck.
DOCTOR SYDNEY HOLT
The hair didn’t have any recognizable root structure that would have the kind of DNA that we analyze in the crime lab.
JOHN QUINONES
(Voice Over) But disappointment is followed quickly by a possible breakthrough. Remember that taunting greeting card? Doctor Holt gets a tentative result from the outside of the envelope that contained it.
DOCTOR SYDNEY HOLT
I can tell you that there’s an indication that there may be DNA from one of the stamps.
JOHN QUINONES
(Off Camera) You could well be on the trail of the Zodiac.
DOCTOR SYDNEY HOLT
Well, it’s, the prospect of being able to contribute to the story is exciting.
JOHN QUINONES
(Voice Over) Then, out of the blue, more good news for Doctor Holt. Our "Primetime" investigation of the case leads to a major discovery. Three more Zodiac envelopes in mint condition. They quietly arrive at the lab after our inquiries with a retired police source. He had kept them in his personal files.
JOHN QUINONES (CONTINUED)
(Off Camera) Now, you have a lot more to work with. It’s got to be exciting.
DOCTOR SYDNEY HOLT
Well, the potential is exciting. Potential is higher now that we have three more envelopes, several more stamps.
JOHN QUINONES
(Voice Over) Exciting because homicide inspector Kelly Carroll and his partner Mike Malone can then compare it with DNA samples from anyone suggested as a possible suspect, something the original Zodiac investigators could only have dreamed of. ;;;
JOHN QUINONES
(Voice Over) But Graysmith also lacks any physical evidence. And nine years ago, Arthur Leigh Allen died without ever being named a suspect by police. However, if Doctor Cydne Holt can find enough genetic material from Zodiac’s stamps and letters, she can compare it to a wafer thin slice of brain tissue from Arthur Leigh Allen’s autopsy.
DOCTOR CYDNE HOLT
This brain tissue from Arthur Leigh Allen is the, the reference sample that I would use for the comparison.
JOHN QUINONES
(Voice Over) Doctor Holt has already detected the possible presence of Zodiac’s DNA in the seal of the envelope that contained the greeting card. And just in case that test fails to produce a full DNA profile, she also prepares to look for DNA beneath the stamps on two of these three letters.
DOCTOR SYDNEY HOLT
Depending on whether those DNAs match each other might allow me to include or exclude Arthur Leigh Allen as potentially contributing the DNA on the Zodiac letters. …
ANNOUNCER
A major breakthrough in the hunt for the Zodiac, when "Primetime" returns.
DIANE SAWYER
And now, the moment of truth. After three decades of guesses, conjectures and suspicions about the notorious Zodiac killer, police investigators will finally know whether he left a telltale clue behind. Will the Zodiac killer finally be revealed?
JOHN QUINONES
(Voice Over) This is the San Francisco Police Department’s DNA lab six days ago, exactly 33 years to the day after Zodiac murdered taxi driver Paul Stine. Doctor Cydne Holt is about to answer the question, did the Zodiac killer leave a genetic trail that could lead to his capture. The answer is yes.
DOCTOR CYDNE HOLT
I found a partial DNA fingerprint from a male individual who at sometime has had contact with the stamp.
JOHN QUINONES
(Voice Over) You’re looking at the Zodiac killer’s genetic identity, the peaks on this graph.
…
JOHN QUINONES
(Voice Over) What Doctor Holt finds is four out of a possible nine DNA markers, plus an indicator of gender. XY means male. Not enough to positively identify anyone as Zodiac. But it’s enough to narrow suspicions or perhaps even eliminate suspects. Next, Doctor Holt compares the partial profile from the Zodiac letter, the pattern of peaks on that bottom row, to a DNA sample from Bay Area school teacher, Arthur Leigh Allen along the top there. You can see they’re distinctly different.
….
JOHN QUINONES
(Voice Over) Zodiac’s partial DNA profile has already eliminated possible suspects. It’s now an invaluable investigative tool…."
I think we can all agree that Television’s goal is to produce an entertaining program which will make money.
Having said that, back to the DNA. Looking at the chart, I am wondering why they have determined the April 1978 letter a fake.
I am also wondering why they thought they did have a partial profile. It must be that all these letters, with a few cells, match each other?
And what about the Exorcist letter, is that not the Zodiac’s DNA? And how do they separate it out from everyone else who handled the
evidence? And what if your suspect did match the 4 markers SFPD has? Would it spark their interest?
Hi-
I’d invite Insp. Hofsass to explain why she thinks they have Z’s DNA. Based on what I know from their effort last year, I find it hard to believe that such is the case. She asked Repetto, who was retiring, to help her expedite the "top secret" DNA testing they were doing last year. This would have been in May or June. Repetto had been around so long that he knew the Chief pretty well. What Repetto told me is that he went to the Chief and said that they needed to expedite the DNA testing because "Mr. X is not going to live forever." So you can judge how seriously SFPD took me and how confident they are in their precious "Zodiac DNA" insofar as ruling people out is concerned. I can only lead you to the water; I can’t make you drink.
The reason they DNA can’t rule anyone in or out is not due to the # of markers. It is because they do not know who the DNA belongs to. That is why they said it "may not be reliable."
Mike
Mike Rodelli
Author, The Hunt for Zodiac; 3.9 stars on Amazon and
In The Shadow of Mt. Diablo: The Shocking True Identity of the Zodiac Killer, a second edition in print format. 4.3 Amazon stars and great Editorial reviews. Twitter:@mikerodelli
It sounds like new SFPD DNA results were obtained last year and that is why Sandy Betts was told that in July.
But no news from SFPD. They must have had something they were anxious about. Did this last round of testing eliminate
KQ? Did anyone ever tell you? One step up and two steps back?
What I understood Mike to say is that while DNA may have been obtained, there is nothing definite to indicate that it is Zodiac’s DNA. DNA could be on one or more of the envelopes from not only LE but from staff at the Chronicle, from the mailroom to the reporters to the publisher, or from any number of postal employees. We are not told where on the envelopes the DNA was obtained from, was it from the envelop flap or stamp being affixed or was it from touch? If it was touch DNA that leaves a wide open field for possibilities.
If LE does not have confidence that the DNA that has been retrieved is Zodiac’s, how can that be used to rule ANYONE in or out as Zodiac?
Hi-
According to an email I got last October from someone with good sources and who has followed the investigation for a long time, there was nothing new to report DNA-wise as of that time. So I doubt Hofsass was saying anything substantive. I know people want to keep hanging me with this DNA but no, he was not "re-eliminated" as far as anyone knows.
I only wish SFPD had the guts to ask him the same questions I did in 2006. That never happened.
"If LE does not have confidence that the DNA that has been retrieved is Zodiac’s, how can that be used to rules ANYONE in or out as Zodiac?"
Nice to see light bulbs going off. 
Mike
Mike Rodelli
Author, The Hunt for Zodiac; 3.9 stars on Amazon and
In The Shadow of Mt. Diablo: The Shocking True Identity of the Zodiac Killer, a second edition in print format. 4.3 Amazon stars and great Editorial reviews. Twitter:@mikerodelli
What I understood Mike to say is that while DNA may have been obtained, there is nothing definite to indicate that it is Zodiac’s DNA. DNA could be on one or more of the envelopes from not only LE but from staff at the Chronicle, from the mailroom to the reporters to the publisher, or from any number of postal employees. We are not told where on the envelopes the DNA was obtained from, was it from the envelop flap or stamp being affixed or was it from touch? If it was touch DNA that leaves a wide open field for possibilities.
If LE does not have confidence that the DNA that has been retrieved is Zodiac’s, how can that be used to rule ANYONE in or out as Zodiac?
I agree. But I do think if they found a suspect, say one with Paul’s driver’s license, and they wanted to help prove he was REALLY the killer…if it actually was Zodiac’s DNA under the stamp, there would be matching traits. False negatives…yes, but not false positives.
“…they may be dealing with one or more ersatz Zodiacs–other psychotics eager to get into the act, or perhaps even other murderers eager to lay their crimes at the real Zodiac’s doorstep.“ L.A. Times, 1969
If anyone wants to read more about the SFPD DNA testing, you can look at this thread which contains the text of two articles–one from 2002 and one from 2007.
It’s the burden of police and prosecutors to prove a person is guilty, otherwise they are assumed to be innocent.
If they lack evidence to connect someone to a crime, such as DNA that doesn’t match or is not from the killer, then they have no basis to conclude that person is guilty.
Some Amateur investigators seem to have it reversed and assume that their suspect of choice is guilty until evidence is presented that proves them innocent. I tend to fall somewhere in the middle and keep an open mind that the work of many amateur investigators have brought forth suspects that could be the killer, but are lacking proof either way.
Where I disagree with people and where the negativity from some towards the work of others is concerned is the idea that others are not so open minded and refuse to accept the possibility that they can be wrong or that other people’s work is just as valid as their own.
I’d suggest – as I have before – that the Badlands or "Citizen" letter is the most important evidence we have, in respect to the letters; the only one likely to carry salivary amylase and so also (perhaps) useable DNA material from being "licked". I hope it’s treated as such by LE. Somehow I highly doubt it. 
