Many Zodiac researchers, amateur or otherwise, have developed their own favorite suspects over the last four decades, but invariably their belief is founded upon circumstantial evidence - and despite the fact many 'coincidences' seem to conspire together to push their suspect into the Zodiac Killer spotlight - it remains just a belief on the part of the researcher and has no basis in fact. Arthur Leigh Allen was a case in point, where multiple evidence lines seemed to suggest he was a strong candidate for the Zodiac murders, however, he was cleared after fingerprints and palm prints, along with DNA failed to match known samples retrieved from the Zodiac Killer letters. But despite this, there still remains lingering doubt on whether or not the samples held in evidence storage are actually that of the Zodiac Killer. Although, if multiple envelope seals and stamps were tested and one single partial DNA profile was unable to be excluded on each occasion, then unless a third party was the donor of saliva, either unwittingly or by consent, the profile of the killer would be close at hand.
Touch DNA requires just a tiny number of cells to be retrieved, although it is a method fraught with contamination issues and the risk of false positives. When dealing with very small samples, the risk of compromising the evidence is greater, with polymerase chain reaction (PCR) often employed to amplify the DNA to create a larger sample for use by investigators.
In the case of the Zodiac Killer, any DNA he deposited on the letters, Lake Berryessa bindings or Paul Stine's taxicab, would today have provided enough DNA for analysis in CODIS (Combined DNA Index System), where the crime scene forensics could be entered into the database to search for a match to an offender already contained within it. However, this technique is totally dependent on the murderer having a previous conviction - otherwise a direct match could never be made. The use of a familial DNA profile has led to the closure of many cold cases, where a close relative has been found on the database and been linked to the current DNA being analyzed through family lines, resulting indirectly to the capture or identification of a criminal, sometimes decades after their crime was committed.
Recent developments have revealed a tantalizing glimpse into the future, offering the possibility to deliver the Zodiac Killer's identity right into the palms of our hands. This has been covered previously, but it will be expanded here in a little more detail. This new technique removes the need for the Zodiac Killer's, or indeed any blood relative to have committed any previous or subsequent crimes - and effectively render the necessity of comparison tools such as CODIS redundant in this instance. It all comes down to the Y chromosome, passed from one generation to another, along the male lineage, in exactly the same manner as ones surname is also passed along. This would providie a correlation between the Y marker and a man's surname, and thereby provide an alternative crime fighting tool - one that could provide us with the exact surname of the Zodiac Killer. This may not deliver the murderer of five people in Northern California on a platter, however, it would at the very least remove all but one of the high profile suspects, and most likely all of them from our Zodiac researchers lists. But how does it work in practice and what are its limitations?
In the case of the Zodiac Killer, any DNA he deposited on the letters, Lake Berryessa bindings or Paul Stine's taxicab, would today have provided enough DNA for analysis in CODIS (Combined DNA Index System), where the crime scene forensics could be entered into the database to search for a match to an offender already contained within it. However, this technique is totally dependent on the murderer having a previous conviction - otherwise a direct match could never be made. The use of a familial DNA profile has led to the closure of many cold cases, where a close relative has been found on the database and been linked to the current DNA being analyzed through family lines, resulting indirectly to the capture or identification of a criminal, sometimes decades after their crime was committed.
Recent developments have revealed a tantalizing glimpse into the future, offering the possibility to deliver the Zodiac Killer's identity right into the palms of our hands. This has been covered previously, but it will be expanded here in a little more detail. This new technique removes the need for the Zodiac Killer's, or indeed any blood relative to have committed any previous or subsequent crimes - and effectively render the necessity of comparison tools such as CODIS redundant in this instance. It all comes down to the Y chromosome, passed from one generation to another, along the male lineage, in exactly the same manner as ones surname is also passed along. This would providie a correlation between the Y marker and a man's surname, and thereby provide an alternative crime fighting tool - one that could provide us with the exact surname of the Zodiac Killer. This may not deliver the murderer of five people in Northern California on a platter, however, it would at the very least remove all but one of the high profile suspects, and most likely all of them from our Zodiac researchers lists. But how does it work in practice and what are its limitations?
When a surname is carried down family lines for generations, an undeniable link exists between the surname and the Y chromosome, so when samples of DNA are retrieved from a current crime scene or from cold cases, they would have the Y chromosome isolated - and bearing in mind its close connection to family lineage - used to reveal a surname. This of course would require a database similar to CODIS, but this time when the Y marker is entered, the possible surname is availed to the observer. The police investigators would then use this to narrow down the field of view, regarding potential suspects and by the same note, remove suspicion from some entirely, thereby reducing man hours and wasted blind avenues.
Research has shown the rarer the surname, the greater the chance a common ancestor is shared. There are nevertheless drawbacks to any technique - in this case adoption and illegitimacy are two such examples - so caution needs to be applied.
The bottom line, is that the confirmed Y marker of the Zodiac Killer may just provide us with the name, that his ciphers promised, but always failed to deliver.
http://www.sciencedaily.com/releases/2008/10/081007192526.htm
http://www.exploreforensics.co.uk/connecting-dna-your-surname.html
Research has shown the rarer the surname, the greater the chance a common ancestor is shared. There are nevertheless drawbacks to any technique - in this case adoption and illegitimacy are two such examples - so caution needs to be applied.
The bottom line, is that the confirmed Y marker of the Zodiac Killer may just provide us with the name, that his ciphers promised, but always failed to deliver.
http://www.sciencedaily.com/releases/2008/10/081007192526.htm
http://www.exploreforensics.co.uk/connecting-dna-your-surname.html
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