The technology of DNA "fingerprinting" has advanced greatly in the past few years.  What I had not realized though, was that the use of DNA fingerprinting in law enforcement is only about 15 years old.

Most of us got our introduction to DNA fingerprinting in the O.J. Simpson case.  The prosecution spent four days allowing experts to drone on and on about alleles and regions and binning strategies, numbing the minds of the jury as well as half the country.

But, it was possible to learn a great deal about DNA during that trial.  I learned that there were two types of DNA profiling, or tests: RFLP Restriction Fragment Length Polymorphism, and the more recently developed STR, or Short Tandem Repeat.  And, according to David Coffman, Supervisor of the DNA Data Bank for FDLE, DNA technology has become even more sophisticated.

It is now possible to test smaller pieces of biological matter and get a DNA fingerprint.  It has also become possible to get a DNA profile from matter which has degraded, or is not fresh.  In addition, the tests are faster and the matching easier because there are more and more data banks.

All fifty states now collect DNA from convicted sex offenders.  Other states collect samples from those convicted of other crimes, usually violent crimes.  FDLE will be going to the legislature this year to ask that burglary be added to the list of crimes that make an offender subject to the gathering of DNA information.  This decision was made after national crime statistics and crime statistics from Florida indicated that about 52% of people found guilty of burglary will eventually be found guilty of a murder or sexual assault.

Twenty states are already linked to a national data base of DNA fingerprints.

The offender data base allows police to find matches of evidence even when no suspect has been identified.  As David Coffman noted: "The investigators used to phone me with names.  Now, I phone the investigators."

DNA evidence is used not only to convict the guilty. It can also be used to free the innocent.  In fact, the number of convicted felons found to be innocent after subsequent DNA analysis of evidence, has caused states to reconsider prior cases.  Some states have even devised Post Conviction Plans which involve going back and taking another look at cases where DNA evidence still exists, or cases where the DNA evidence would be pivotal.

There is no real controversy among the scientific community about the validity of the DNA profiling, but there is a lot of controversy about how this evidence should be used in courts.  In some cases, juries simply ignore the DNA evidence, in others, it is crucial in the jury's decision.  Part of this may be that the probability statistics used by the experts do sound unbelievable.  Even though the experts called to testify are using the most conservative estimates, when an expert gets on the stand and says that the probability that another (non-related) person could have a DNA fingerprint that would be the same is one in 4 billion (or more), many jurors probably just don't believe that anybody can know anything to that amount of certainty.

The debates about use of DNA evidence, the advances in the technology and the objections to the collection of DNA evidence as an invasion of privacy should be interesting to follow in the coming years.