Is DNA Evidence Reliable?

DNA has become a major tool for use by police in solving cold cases of murder and other violent crimes. In the past year, about 50 cold cases have been solved nationwide using public genealogy websites. But is this evidence alone reliable?

James H. Manahan, J.D., has written an article in the Lake County (Minnesota) News-Chronicle that tells why DNA evidence alone can be misleading. Manahan cautions that DNA is a great tool but also must always be used in conjunction with old-fashioned police work.

Manahan describes a case when a homeless man was accused of murder, based upon DNA evidence from a 7-year-old cold case. Luckily, the man’s public defender found a subtle problem with the evidence. In short, the DNA evidence obtained was “identified” as coming from the wrong man. Instead of spending the rest of his life in jail, the homeless man was quickly cleared of the crime. Had the public defender not been suspicious, the outcome could have been far different.

The article quotes DNA and genealogy expert CeCe Moore. It also quotes the homeless man, Lukis Anderson, when he got out of jail: “There’s more that’s gotta be looked at than just the DNA. You’ve got to dig deeper. Reanalyze. Do everything all over again before you say, ‘This is what it is.’ Because it may not necessarily be so.”

You can read this interesting story at:


Perhaps the question is not whether DNA is reliable, but how does the DNA evidence fit with all the other evidence, historical context, and other material evidence. Science, the law, and other disciplines seldom rely on just one piece of evidence as “proof.” If any of the pieces do not fit, then those inconsistencies need to be resolved or explained.


It is important for the average person who may one day be called to serve as a juror to understand that while DNA technology is a wonderful scientific advance, it can still be misleading or fallible because the collection and analysis of DNA samples is conducted by human beings, using tools manufactured by other human beings. We’re still learning of new ways in which, despite everyone’s best efforts, things can go off the rails.


DNA test results also affect personal results. Testing was done on me and my husband a year or so ago. I took it with a grain of salt because for the most part my results reflected what I had been told all my life. A few days ago, we both received updated results. The new results in hardly any way match what we originally received. I am wondering how the results could have changed so drastically. I now show Swedish, Finnish results and have now idea from who. Yes, I know that there are advances in the DNA analysis but I am rather shook at how the original results have changed so much.


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