In the aftermath of the disappearance, the search for Donna Lass would be badly affected by the inclement weather in the coming months, highlighted by Police Chief Ray Lauritzen in the newspapers from the outset: "We don't know where we're going to begin. There's a four or five foot pack of snow out there and it's still snowing heavily. There's no point to a search at this time. It's unlikely a victim would be uncovered before spring."
Similar to the second and third crimes by the Zodiac Killer, the disappearance of Donna Lass was again followed by a phone call from the supposed perpetrator. But unlike Blue Rock Springs Park and Lake Berryessa, this phone call didn't brag about his crime, it claimed Donna Lass had been 'called away' or 'called out of town' due to a family illness, all of which was subsequently proved to be false. The caller was seemingly trying to give the impression nothing sinister had happened, suggesting the act of the phone call was simply to 'buy time'. If the abductor was affording himself some extra breathing space, then the real possibility he was local to the area or known to Donna Lass is a credible argument, and he was either holding Donna Lass at this juncture, needed time to dispose of her body, or possibly needed to remove incriminating evidence from his home or vehicle before the police came knocking. This may have suggested that the responsible moved in the circle of Donna Lass, such as friends and work colleagues, who are inevitably the first people to be questioned in most police investigations.
The nature of the call was also suggestive of a perpetrator who knew Donna Lass. A friend or work colleague through conversation or private details, would be privy to information about her family, and the fact they lived in Sioux Falls, South Dakota, 1,555 miles away. A phone call in this instance, using a family illness as a ruse, would be of the utmost benefit to the caller, possibly 'buying' the perpetrator plenty of time. The caller it would seem, knew her family did not reside in South Lake Tahoe or nearby, because this would have made the call ineffectual.
Two phone calls were laid, one to her employer and one to her landlord. The first would obviously explain her absence from work after the Labor Day weekend, the second would possibly allay the concerns of her landlord over rent collection. He may have known Donna Lass, but would unlikely have known the exact date her payments were due. The fact he called her landlord at all, is indicative of somebody who was familiar with Donna Lass, unlikely to be known by a random killer or abductor, who just turned up at the Sahara Tahoe Hotel that morning. If the perpetrator was the Zodiac Killer, then his close ties to Donna Lass could be of crucial importance, bearing in mind the widely held belief he was unknown to his victims in the first four confirmed attacks in the Bay Area. If the Zodiac Killer was also known to Cheri Jo Bates, due to the specific targeting of her Volkswagen Beetle, then Riverside and South Lake Tahoe may be more closely linked than ever imagined.
The fact she was targeted immediately on her shift change at around 1.50 am is also telling. Had a nurse just vanished from the start or middle of her shift, this would obviously have raised a red flag with the Sahara Tahoe Casino, negating the intention of the abductor, and most certainly rendering the phone call unnecessary and highly suspicious. She had already changed from her nurses uniform into her civilian clothes, as her shift was due to end at 2.00 am, something the perpetrator likely knew.
The last person apparently to see Donna Lass before her disappearance was a Joan Bentley from San Francisco, who stated that Donna appeared in good spirits at approximately 1.40 am. The last entry on her log according to her sister, Mary Pilker, was "patient complains of", before the pen trailed off the page. This pen mark is unlikely to have been created by her being physically manhandled from the casino, as it was extremely busy during the Labor Day weekend. More likely, is that somebody approached her nurses station and asked for medical assistance in the car park. Donna Lass may have been writing in her nurses log, when she had her arm tugged in a gesture of 'please help,' or had been in the middle of writing, when she abruptly rushed off to aid the concerned citizen. Either way, her pen trailed down the page.
Was the perpetrator aware of her plans to meet Jo Anne Goettsche at around 2.00 am inside the casino, so acted just before the end of her shift. The subsequent phone call may then have served an extra purpose of allaying the worries of Jo Anne Goettsche, had she informed the casino of her concerns or contacted the police. If the perpetrator knew of Donna Lass' arrangement with her friend, he may very well have spoken to her in the preceding days, further cementing the idea he was known to the young woman.
Six and a half months after her disappearance, the 'Pines' postcard was mailed by the Zodiac Killer or an impostor to the San Francisco Chronicle on March 22nd 1971. But why did the likely killer of Donna Lass wait this long to mail the communication. Did his closeness to Donna Lass play any part?