Daily Archives: June 12, 2009

DNA, a Bloody Bat, and CODIS

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:

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Posted by on June 12, 2009 in DNA, Interesting Cases

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