Here's the Zodiac
DNA is last hope of proving slayings


San Francisco Examiner


May 18, 2001
By ZoŽ Mezin

All indicators point to Arthur Leigh Allen as the infamous Zodiac killer who murdered five people in the Bay Area in the late 1960s and bragged about it in letters to The Examiner and Chronicle. Armed with DNA evidence from the San Francisco Police Department's DNA crime lab, investigators may be on the verge of proving it.

Saliva unwittingly left on the envelopes of those letters may provide the missing piece to a puzzling case that has befuddled investigators for more than three decades. Shortly after San Francisco police Inspectors Michael Maloney and Kelly Carroll were assigned the Zodiac killer case Aug. 29, 2000, they sent several of the white envelopes to the DNA lab for analysis. One suspect's DNA also was sent to the same lab.

Though police are tight-lipped on whose DNA was sent, Vallejo police Lt. JoAnn West, acting spokeswoman for the intercity Zodiac task force formed in 1998 by police agencies in San Francisco, Vallejo, Napa and Solano counties, confirmed that police have DNA samples taken from Allen.

Arthur Leigh Allen "is a primary suspect in the case, but that's all he is," said West in a telephone interview Thursday. She would not say if police have DNA samples from other suspects.

Because the case has garnered so much public attention and launched a thousand theories, San Francisco police are proceeding with caution. They are not releasing any names.

"If we point the finger at one suspect and it isn't him, that could be used in a case against a second suspect," Maloney said.

Still, tidbits of information have come to light.

While refusing to reveal the name of the principal suspect, he said that "he's been a suspect for a long time. People have talked about his name."

Allen, a former Vallejo schoolteacher, long has been considered by investigators to be the most promising suspect.

But he died in 1992, apparently taking his secrets with him. Those secrets may soon be revealed by the San Francisco Police Department's crime lab.

If Allen's DNA matches that from the envelopes, the lab may be credited with solving one of the most infamous serial killer cases of the century.

In the late 1960s, terror swept the Bay Area as a mysterious killer began brutally slaying young people.

The killer fanned the flames of fear by sending 21 letters about the savage slayings first to The Examiner, then to The Chronicle. The letters revealed details about the murders that only the killer would know. Further, as if to quell any doubts, the killer enclosed in each envelope grisly proof of his authenticity -- swatches of cloth snipped from the most recent victim's clothing.

Investigators strongly suspected that Allen was the killer but had no way of analyzing genetic evidence confiscated from his apartment in the 1970s and shortly before his death.

One of three DNA scientists in San Francisco's crime lab has been asked to analyze the DNA samples. And though police aren't releasing that person's name either, Bonnie Cheng, the criminalist whose work provided the key proof that led the San Francisco District Attorney's Office to issue a warrant for the arrest of a suspect in a 22-year-old cold homicide case, says it's not her.

Cheng is not on the case, but she is well-versed in the methods to process an envelope for DNA.

First, pieces of the stamp and envelope flap are cut out and placed in a vial containing saline solution, used to test for the amylase enzyme. Great quantities of this enzyme are found in saliva.

Meanwhile, the scientist must also place the fluid under a microscope to see if it contains nucleated cells. These cells, found all over the body -- in muscles, organs, the vaginal cavity and, incidentally, inside the mouth -- contain the actual DNA needed to create a personalized DNA profile.

Once confirmed that the DNA is present, the scientist must release it, count it and then replicate the sometimes trace amounts of genetic material.

The polymer is passed through a genetic analyzer that creates a computerized DNA profile. This "genetic fingerprint," which resembles a line-graph with peaks and valleys, can then be compared to a second profile.

If done nonstop, each sample should take two entire days to process and 30 minutes to analyze. But lab scientists don't have the luxury of working solely on one case at a time. Current cases often take priority over cold cases, Cheng said.

Police are still awaiting the results of the DNA analysis, which was expected this February but should arrive any day now.

There's good reason for their excited anticipation. A match, if made, would be almost conclusive.

"One difference (in the two profiles) is enough to exclude someone," Cheng said. "It's very clear cut."