I've never seen Donna Lass as a Zodiac victim. She just doesn't fit. Too many deviations from his usual pattern. I've always believed Cheri-Jo Bates was a probable Zodiac victim, especially since the Riverside Police Department's long-time favourite suspect was recently ruled out with DNA evidence (taken from some male hairs clutched in her hand, almost certainly from her attacker). And I also believe the June 4 1963 double-murder of Linda Edwards and Robert Domingos in Santa Barabara county was an early Zodiac crime - possibly his first. That particular case has Zodiac written all over it. The victim profile, the MO, the location - it all fits with Zodiac's later attacks on young couples. Granted, he showed he was willing to break his own mold when he murdered cab driver Paul Stine on a busy San Fran Street. But Lass, to me, is not a compelling possibility. I'd need to see some convincing evidence before I even considered her a Z victim. Thus far I have not.
I note that Darkblue above has linked to Mike Butterfield's site: Zodiackillerfacts.com IMO, that is the site for solid, objective information on the Zodiac crimes. Mike has always taken great pains to maintain an open mind, while taking a good, hard, skeptical look at the facts, thus presenting the evidence as it is, not as he wishes it to be. That is something that can be said about few other "zodiolgists". In many ways, Zodiac is one of the most frustrating cases to discuss online. I was relieved to wade through this thread and not see a bunch of speculation based on what Darlene Ferrin's two wacky sisters decided to make up years after the fact. There have been far too many pixels wasted rehashing the ever-changing stories of those two flakes: strange men showing up at Darlene's parties, stalkers, "strangers" lurking and learing at the restaurant where she worked, etc. Mike Butterfield has examined the original police reports, including the original interviews with the sisters and friends of Darlene Ferrin. NONE of those stories were shared with police in the days and weeks and months after the crime. Not until the 1980s did they start coming up with those stories. Some of their nonsense even made its way into John Douglas's book.
And then there are the Arthur Leigh Allen devotees. Yes, he was a fascinating suspect. He was also ruled out by every piece of forensic evidence developed from the crime scenes and the known Zodiac letters. Handwriting analysis ruled him out as author of the letters. His palm print did not match the "writer's palm" recovered from one of the letters. His fingerprints did not match the bloody print found at the Stine scene. Finally, his DNA did not match DNA recovered from the stamp of one of the known Zodiac letters. It wasn't him. But thanks in large part to Robert Graysmith's Zodiac Unmasked, largely a self-serving historical fiction, and the (admittedly excellent, though even more sensationalized) movie based on the book, millions remain convinced of Arthur Leigh Allen's guilt.