The 1989 murders of two Philadelphia women were "cold cases" until 2013, when Philadelphia police say they matched DNA from a federal database to a New Jersey man. Prosecutors contend that the man, now 54, left his DNA on the sneaker of one of the victims, a 33-year-old, when he strangled her with a shoelace and left her in a burned-out bar.
The defendant's DNA was also been linked to evidence found near the body of another woman. The 19-year-old woman was found raped and strangled to death in an abandoned car a month prior. The areas where both women's bodies were discovered are known to be frequented by prostitutes and drug users.
Early this month, the man was convicted of both murders and sentenced to life in prison. He expressed regret to the victims' families for their losses. However, he said that, despite his criminal past, he did not murder the women.
The attorney for the defendant argued that there were multiple flaws with the theory that her client was responsible for the murders based on the DNA results. She contended that the defendant's DNA could have been left on the ground from something as simple as spitting and been transferred to the pieces of evidence that reportedly contained it. The DNA analyst also testified that the DNA was from multiple sources.
While the odds required for a DNA "match" can be overwhelming, it can be easily left at or transferred to a location. Thus, it can appear that people were present at a crime scene when in fact they weren't. Experienced Pennsylvania criminal defense attorneys can work to show that, even with a DNA "match," there can be reasonable doubt of a person's guilt.
Source: Philly.com, "Defense challenges DNA in 'cold case' trial," Joseph A. Slobodzian, April 29, 2016