There was a trail of blood traveling from the crime scene to Terracina Drive. Investigators came to the conclusion this was the direction of the killer after the brutal attack. It may have been a blood trail from the victim, dripping from the knife or such-like. But it could equally have been a trail of the perpetrator’s blood, having cut himself during the attack. If investigators had retrieved this blood and stored it correctly, it could have answered many questions and also have been used to eliminate suspects. DNA wasn’t available in 1966, but blood typing was a routine test. Taking samples from different locations of Cheri Jo Bates’ clothing and the blood trail to Terracina Drive, could easily have determined whether this was the killer’s blood or not.
Cheri Jo Bates’ blood type was AB RhD positive, which accounts for only 3.4% of the American population.
This makes it 96.6% likely, the killer was of a different blood type, making it a reasonably simple task, even in 1966, of identifying a separate donor, had he cut himself in the commission of the crime. Whether this trail of blood was ever retrieved is another matter, but had it been, even without DNA, many questions could have become answers. The rarity of Cheri Jo Bates’ blood type was the perfect opportunity for the investigators in 1966 to identify any possible blood deposited at the scene by the killer.