This murder was only the tip of the iceberg, that began 47 days earlier, when the body of Rosa Vasquez (20) was discovered close to the Arguello Boulevard entrance to the Golden Gate Park on May 29th 1973. She had been strangled and thrown from the nearby road. Almost three years earlier, Donna Ann Lass disappeared from the Sahara Tahoe Hotel on September 6th 1970 after finishing her shift as a nurse. A few months earlier in June she had moved to South Lake Tahoe from San Francisco, where she had previously been employed as a nurse at the Letterman General Hospital in the Presidio, near the Paul Stine murder scene. Curiously, Rosa Vasquez was also employed at the Letterman General Hospital as a keypunch operator. A keypunch is a device for delivering punch holes at specific locations on a card face, to carry information for a relevant task. This was apparent on two cards possibly mailed by the Zodiac Killer, when the 13-Hole postcard was received on October 5th 1970, along with the Pines card on March 22nd 1971, albeit prior to the murder of Rosa Vasquez. She had been a resident of 834 Bush Street, close to the collective of the Good Times newspaper at 2377 Bush Street, where Zodiac suspect Richard Gaikowski worked as an editor for the publication (although the Good Times had produced its last offering by the turn of 1973).
Finally, Angela Thomas (16), a resident of Belton, Texas had traveled to San Francisco for brief stay. After a day out in Hayward she visited friends in the Presidio district of San Francisco, but neither of her friends were home at the time and she was last seen walking away from the area at 9:00 pm on Sunday, July 1st 1973. She was found naked and smothered the following day in the grounds of the Benjamin Franklin Junior High School.
All four had a military connection, a trait often associated with the Zodiac Killer due to a number of factors, which included the Wing Walker footprint impressions taken from the Lake Berryessa crime scene, the Riverside alleyway heel print at the site of Cheri Jo Bates' murder and the possible links to the Vandenberg Air Force Base, due to the lot number of the unspent ammunition at the scene of the Domingos/Edwards murders in 1963.
Nancy Gidley was stationed at Hamilton Air Force Base, Marin County. Rosa Vasquez was a keypunch operator at Letterman Army Hospital. The father of Angela Thomas was an army sergeant, previously based at the Presidio. And finally, Yvonne Quilantang was having a relationship with a soldier from Missouri (albeit not a strong connection). There is no evidence to suggest that any of these four victims were Zodiac crimes, although there is reason enough to consider these four murders may have been committed by a single perpetrator, due to numerous similarities and occurring within such a short time frame.
Some researchers believe that Lawrence Kane and the Zodiac Killer may be one and the same, trailing Donna Lass from San Francisco to South Lake Tahoe, having lived at 217 Eddy Street, close to Mason and Geary Streets in San Francisco at the time of the Paul Stine murder. Latterly, working near the workstation of Donna Lass at the Sahara Tahoe Hotel according to former law enforcement officer Harvey Hines. Is it possible he returned in 1973?. Both Donna Lass and Rosa Vasquez murdered, having worked at the same hospital, inside of three years seems unusual, albeit probably coincidental. The identity of the Zodiac Killer may never be known, but did he continue his reign of terror beyond the murder of Paul Stine on October 11th 1969?