Imagine a day when hardly anyone is able to get away with murder. Think about that. If there were a way to almost guarantee a killer would be discovered and punished, wouldn’t the murder rate go into freefall decline?

Frivolous thinking, you say? Well, consider the forensic crime-fighting advances that have been developed in recent years.

Homicides considered to be unsolvable are now being solved. Years-old cold cases are becoming red-hot again. Advances in DNA science allow creative genealogists to use DNA in all sorts of amazing ways to identify both the nameless dead and long-sought violent crime suspects. Guilty parties are being identified, spontaneous confessions are being given and survivors are finally getting answers.

DNA technology was first used as a powerful crime-fighting tool in 1986. That year, Englishman was convicted after forensics testing matched his DNA to semen found at the scenes of two fatal rapes in the English midcountry. In 1988, the first DNA conviction was won here in the United States when Tommie Lee Andrews of Florida was convicted of raping and stabbing a woman.

In the beginning, it took a relatively substantial sample of blood, semen, saliva or other bodily material to identify a suspect. But over time, science has required smaller and smaller samples. In recent years, so-called (or Trace DNA) was developed. Identification can now be made from as few as a half-dozen skin cells left behind by a perpetrator after he or she has touched an object at a crime scene.

The most mind-boggling DNA-related cases these days have come with the partnership of forensic scientists and genetic genealogists. Once DNA has been gathered from a crime scene, a living person or an anonymous body, genealogists can build a virtual family tree of the donor’s relatives. Suspects can then be culled from that family tree, and genealogists can even provide physical details of what they look like.

In the so-called , a 10-year-old boy’s body was found discarded along a North Carolina highway in 1998. Thanks to a determined sheriff’s detective and an enterprising genealogist’s DNA breakthrough, the child was finally identified last year as Bobby Whitt. His father has now been charged with Bobby’s murder and is also a suspect in the murder of the boy’s mother.

A DNA family tree discovery finally ended the 30-year spate of killings by the in Wichita, Kan. After detectives zeroed in on Dennis Rader as the killer, they learned that his daughter had recently undergone a gynecological test at a local clinic. They got a court order for her DNA. It was a familial match to the DNA collected from BTK’s crime scenes. When confronted, Rader simply said: “I’m BTK. You got me.”

After a massive four-decade police investigation, a suspect in the case of the so-called was finally identified through the painstaking task of uploading the unknown killer’s DNA to publicly available genealogy websites. The killer’s great-great-great-grandparents were identified. Then, 10 to 20 distant relatives with partial DNA matches were located. And finally, detectives and genealogy experts narrowed them down to just one suspect. Joseph DeAngelo, 72, a disgraced former police officer, was arrested. He’s now awaiting trial, accused of at least 50 rapes and 12 murders committed up and down the California coast.

In addition to the millions of DNA samples stored in federal and state databases, more than 20 million more samples have been deposited by those looking for relatives on private DNA registries such as , and a clearinghouse registry called . These online sites have been a boon to detectives who are looking to match unidentified crime scene DNA with someone on the criminal’s family tree.

This breakthrough in DNA sleuthing has successfully identified more than 70 criminal suspects during the past 18 months, yet it has critics. Some genealogists sharply criticize their colleagues who work with law enforcement for supposedly going outside the profession’s boundaries. Some customers of the ancestry sites are angry that their genetic sample was used to arrest family members. Operators of the sites are miffed that their databases are now swimming with unknown profiles uploaded by detectives. Some registries now ask customers to give their explicit permission that law enforcement can include their DNA profile in a search.

Privacy advocates warn that the family tree procedure amounts to Big Brother “genetic surveillance.” In response, new federal rules for familial DNA searches are now being developed, funded by grants.

It still puzzles me, though, that anyone would want to stymie an investigator searching for a serial rapist or murderer. No one should get away with such crimes.

Coupling DNA advances with DNA genealogy has been called the biggest crime-fighting breakthrough in recent history. To restrict this innovation and risk leaving violent criminals on the loose is madness.

— is the author of three books, including , which is now updated with new chapters and is available as an audiobook. Contact her at , or . The opinions expressed are her own.