In 1997 Susannah Chase was walking home from a pizza parlor in Boulder, Colorado. She never made it. She was found brutally murdered and raped, having been severely beaten with a baseball bat. She suffered at least four skull fractures, survived for a brief while, but ultimately succumbed to her injuries. A bloodied bat was found at the crime scene.
Flash forward to 2000 and a state away. Diego Olmos-Alcalde was arrested in Wyoming for kidnapping another woman. In 2001 he was convicted and sentenced to 10-20 years in prison. The Wyoming Supreme Court overturned that decision on a technicality and he was retried in 2004. He was again convicted and given a sentence of 7-10 years, with credit for time served.
Now back to Colorado where DNA from semen obtained from Susannah Chase was subjected to genetic evaluation by a company known as DNAPrint Genomics in Florida. They applied new techniques that allow some degree of racial discrimination from a DNA profile. Their determination was that the semen found in Chase came from a Hispanic or Native American.
Flash forward one more time to 2008 when Olmos-Alcalde’s DNA profile was entered into the Combined DNA Index System ( CODIS). There was a hit. Olmos-Alcalde’s DNA matched that of the semen sample taken from Susannah Chase. Olmos was arrested and now is on trial for the 1997 rape and murder of Chase.
A word about evidence: According to the Locard Exchange Principle, the heart and soul of forensic science, whenever an individual interacts with another person, place, or object there is an exchange of material. This may be simple hair and fiber, or maybe footprints, fingerprints, or tire tracks, or, as in this case, bodily fluids such as blood, saliva, or semen. But all the evidence does is create a link between an individual and another individual, place, or object. It is up to the courts to determine what this link means. This case is becoming a classic example of this type of evaluation.
The DNA evidence is as follows:
DNA from the semen found in Susannah Chase is that of Diego Olmos-Alcalde.
DNA found on the baseball bat, the murder weapon, matched the DNA of Olmos-Alcalde’s girlfriend and an unknown male. There was no DNA on the bat from Olmos-Alcalde.
How do we sort through all of this? Olmos-Alcalde admitted having sex with Susannah Chase but denied killing her. A wise move by either him or his attorneys, since the DNA absolutely connected him to the victim and if he denied knowing her or ever having been near her, he would have a problem. So the DNA findings do not dispute his story. The mere finding of his semen in the victim does not mean that he raped or murdered her only that sexual intercourse took place. It does connect him with the victim but that’s all it does.
But what of finding DNA from Olmos-Alcalde’s girlfriend on the bat? Witnesses said that she owned a bat similar to the murder weapon and her DNA connects her to the bat used to kill Chase. And since she and Olmos-Alcalde had a relationship, he had access to this particular bat.
The finding of DNA from an unknown male on the murder weapon is problematic for the prosecution. Is this DNA simply from someone the girlfriend knew, someone who had been in her home and handled the bat, in which case it is a classic red herring. Or is it the DNA of someone unknown to her and Olmos-Alcalde? Someone who could be the real murderer. Olmos-Alcalde could have had sex with Chase, left her to walk home on her own, where she encountered another male who committed the murder.
Evidence, besides making a connection, can also be additive and cumulative, meaning that the more evidence that piles up the worse it looks for the defendant. In this case, Olmos-Alcalde cannot and does not deny that he had contact with Susannah Chase. His DNA makes that clear. His defense will obviously be that the unknown male killed her after he had had innocent sex with her.
But does this seem plausible? What are the odds that an unknown male stole the murder weapon from the girlfriend’s home and used it to kill a young woman that Olmos-Alcalde had just had sex with? Would that even work in fiction? Maybe, if you’re writing a story where someone is framed, but logic is against this actually happening. What are the odds? Lottery ticket odds, particularly since the police questioned more than 500 people and took DNA and hair samples from 30 men, including a homeless man found in the alley near the crime scene. Further complicating the picture, this unknown male DNA could have been on the bat for months, even years if the bat were not used or cleaned in any way.
The DNA connects Olmos-Alcalde directly to the victim and indirectly to the murder weapon. Now the jury must decide what these connections mean. This will be an interesting case to follow as it unfolds.