More than 125 years ago, the great American author Mark Twain wrote of a killer identified by his own thumbprint. “There was one thing about a person which never changed, from the cradle to the grave,” Twain wrote of the loops and whorls unique to every individual fingerprint.

Here as in so other ways, Twain was a man ahead of his time. When he published Life on the Mississippi, criminalists were still using photographs and body measurements as a means of singularly identifying individuals. It would be almost a decade before fingerprinting was successfully used in a criminal investigation and eventually surpassed every other means of personal identification.

But writing in 1883, Mark Twain could never have known about the other thing about us that never changes from cradle to grave: our DNA. Today, in 2012, it’s possible to test a piece of biological evidence and identify the person who left it to the exclusion of any other person on the planet.

Unfortunately, Massachusetts law has yet to catch up fully with that science. A DNA profile can be obtained from a person’s inner cheek quickly, easily, and inexpensively with just a cotton swab. But our laws on this important evidence demand that a licensed phlebotomist take the sample in a blood drawing. This 19th century approach to 21st century science has left us with a backlog of tens of thousands of convicted felons yet to submit their court-ordered DNA samples.

For more than 100 years, every person arrested for a misdemeanor or a felony has had his or her fingerprints and photograph taken. In most states and federal jurisdictions, arrestees must also provide a DNA sample, and here Massachusetts is again behind the times. DNA evidence has repeatedly shown its value, not only to identify the guilty but to exonerate the innocent, and these weigh equally in my support of expanding our use of this neutral, independent, and exacting scientific evidence.

Critics falsely claim that a DNA profile could reveal information about an offender’s family history, medical conditions, or other private information. In fact, the DNA profiles we use in law enforcement they tell us nothing more about a person than who he or she is.

In 2008, an unknown attacker broke into a home in Boston and violently raped two women, leaving behind DNA evidence unmatched to any known offender. Two years later, in 2010, he struck again in Cambridge, nearly killing an adult and a young child. As he had before, he left DNA at the scene. This time, though, he also left fingerprints that police soon matched to the ones he’d provided when arrested on a previous charge.

Had this offender been ordered to provide a DNA sample along with his fingerprints when first arrested on the unrelated offense, his unique genetic identifier would have been available in 2008 to identify him as the Brighton rapist and he would not have been free to victimize two more people in Cambridge years later.

This is the power of DNA evidence. These are the crimes it can solve and the tragedies it can prevent. This is why Massachusetts must step out of the past.