http://www.huffingtonpost.com/2013/01/1 … 75208.html
"The color of the eyes and hair of ancestors dead for hundreds of years can now be revealed from their DNA alone, researchers say". We know that Arthur Leigh Allen was ruled out using fingerprint and DNA analysis, when a sample of his brain tissue was tested, however it is well known that hair color, eye color, geographical ancestry, predispositions to disease, height etc can be determined with a fair degree of accuracy.
"For instance, the researchers analyzed DNA from Gen. Wladyslaw Sikorski, who was born in 1881 and died in 1943. During World War II, Sikorski was commander-in-chief of the Polish Armed Forces and was also prime minister of the Polish government in exile. He died in an airplane crash at Gibraltar. By analyzing genes from one of his teeth, the researchers confirmed he had the blue eyes and blond hair seen in portraits painted many years after his death.".
But this is not all "It is also possible, or might soon be, to predict skin color, freckling, baldness, hair curliness, tooth shape and age. Computers may eventually be able to match faces generated from DNA to those in a database of mug shots. Even if it does not immediately find the culprit, the genetic witness, so to speak, can be useful, researchers say."
This is promising considering the advancement of genotyping in recent years, but at the very least, if we can determine say hair and eye color, then at least some of the current Zodiac suspects could be already ruled out. It could also indicate whether the various descriptions of the Zodiac are credible, including the Presidio Heights sketch.

Also 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 new technique removes the need for the Zodiac Killer’s or indeed any blood relative to have committed any previous or subsequent crimes and 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. Thereby providing an indelible connection between the Y marker and a man’s surname, as an alternative crime fighting tool, and 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 or most likely all of them from our Zodiac researchers lists.
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, 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 his name.
http://www.exploreforensics.co.uk/conne … rname.html
http://www.nytimes.com/2015/02/24/scien … n-dna.html