DNA profiling

People who kill become confident after the passage of years. Many have moved to other regions of the country away from where they committed their crimes. Some have gone on to raise families and become accepted and respectable members of their community. In many cases, the original investigators have moved on in their careers, retired or died, according to Richard H. Walton, author of “Cold Case Homicides: Practical Investigative Techniques.”

While those who murdered may try to forget and put their past behind them, others have not. Family and friends of the murder victim never forget. Neither does law enforcement. Suspects who thought they got away with crimes in the past didn’t anticipate DNA or computer databanks. Many in law enforcement believe that DNA is the most significant advancement in criminal identification since the fingerprint, notes Walton.

While DNA is often used to link suspects to crime scenes, it can also be used to identify missing persons like Roger Ellison. Every single cell in our bodies contains DNA, the genetic material that programs how cells work. Here’s the kicker – 99.9 percent of human DNA is the same in everyone. That means only 0.1 percent of our DNA is unique. Each human cell contains three billion DNA base pairs. Our unique DNA, 0.1 percent of 3 billion, amounts to 3 million base pairs. This is more than enough to provide profiles that accurately identify a person. The only exception is identical twins, who share 100 percent identical DNA, according to the Genetic Science Learning Center at the University of Utah.

Nuclear DNA comes from the cell nucleus and is inherited from both parents. A lesser known form of DNA testing called Mitochondrial DNA is only inherited from the mother. Scientists usually test nuclear DNA first. The problem is that nuclear DNA can be easily damaged by extreme heat and other conditions. Mitochondrial DNA can often be found in very small or damaged DNA samples and is used as a backup when other test results are inconclusive. The DNA testing process is lengthy, sometimes taking months. Despite scientists’ best efforts, some testing may not prove successful, according to the National Institute of Justice website.    

nuclear-dna-2-crop1

mitochondrial-dna-2-crop

National Institute of Justice

 

The Colorado Bureau of Investigation is currently conducting DNA testing on human remains found in Chaffee County, Colo., to see if it’s a match with Roger. The unidentified John Doe is estimated to be about 17 years old with a similar build. Scraps of clothing found near the bones resemble what Roger was last seen wearing on the day he disappeared.

When analyzing bones, a forensic anthropologist must first determine what the person’s gender is. Generally, males have larger bodies and heavier bones than females. Growth and development of teeth and bones proceeds at a fairly predictable pace, so it’s not too hard to estimate the biological age of a growing child within a narrow range. Race, on the other hand, can be difficult to determine because living populations have few clear distinguishing features and most of those are soft-tissue features. Height is calculated using the measured length of a long bone such as an arm or leg. Weight is difficult to estimate, but clothing may give way to some clues, says Walton.

Every person’s skeleton is unique due to genetics, growth and development, health, nutrition and lifestyle. In Roger’s case, a previously fractured leg may prove helpful in making a positive identification.

Read how DNA samples are helping to crack cold cases on the America’s Most Wanted website at AMW.com | DNA Samples Help Crack Cold Cases.

Lori

Coming up: Profile of a killer

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