INDIANAPOLIS (AP) - Imagine if criminals conveniently left calling cards at crime scenes that helped describe the culprits.
Barring video or photographic evidence, the closest investigators have come to this dream has been the often unreliable observations of eyewitnesses.
Now, however, an Indiana University-Purdue University Indianapolis professor has helped develop a forensic tool that aims to take a small amount of DNA and determine the hair color, eye color and skin tone of the person who left it.
Working with colleagues at Erasmus MC University Medical Center Rotterdam in the Netherlands, Susan Walsh designed a method that will allow scientists to take biological samples and predict three of the most commonly used descriptors for a person.
“It’s like using an eyewitness report just like we use every day,” said Walsh, an assistant professor of biology in the forensics program at the IUPUI School of Science. “Instead of an eyewitness, it’s a biological witness.”
Some similar commercial tools exist, but the HIrisplex-S DNA test is available free online for other forensic scientists to use. And its developers disclose exactly how it works, Walsh said. Previous tests exist for hair and eye color but did not include skin color.
The predictive tool can be used in cases in which investigators have an evidence sample but no reference DNA that matches the sample.
Police investigators in the Netherlands, Poland and Australia have adopted the technique, Walsh said. They do not rely on it as evidence in court but use it to help narrow down the physical characteristics of the criminal for whom they are looking.
In Indiana, Walsh has started exploring whether the method might be of use to investigators for cold cases.
“If you have a cold case that’s just sitting around, why not try something else,” she said. “This is phenotyping. It could change the whole direction of an investigation.”
The Indiana State Police Laboratory has shared some samples from its cold case files with Walsh’s lab to see whether the tool can assist in any way.
When the tool returns results, the lab passes on the information to the police agency under which the case falls.
“All we would do is say here is information from the DNA testing. This may help point you in the direction of how to investigate your case,” said Indiana State Police Capt. David Bursten.
Unlike some of the commercial tools, the HIrisplex-S DNA website does not profess to generate an approximate image of the person associated with the sample. Nor does it provide any information about the person’s ancestry that could be used in an attempt to identify him or her.
In that regard, the information gleaned from it is little different than what a photograph would yield, said David Kaye, a distinguished professor at Penn State Law.
“The approach that’s taken - to look at particular features of the genome that might be associated with skin color - is in some ways less objectionable than efforts to trace geographic ancestry and race, which is less predictive of skin color,” he said.
Because the test looks at such traits rather than a person’s ethnicity or race, Kaye said, he does not view it as raising “huge ethical issues.”
This most recent test predicts what color skin a person has divided into five subtypes: very pale, pale, intermediate, dark and dark to black. Walsh compared it to choosing the shade of a paint chip rather than making a prediction about race or ethnicity.
Still, police agencies will need to recognize that the tool offers probabilities, not definitive answers, and not place undue weight on the results, Kaye added.
Another downside of the new test is that it requires a larger sample than is often available, said Paul Misner, biology section supervisor for the Indiana State Police Laboratory.
In addition, it requires about 10 times as much DNA as some of the other analyses the lab can perform, Misner said, adding that he also was not sharing samples that had DNA from more than one person since the results could prove confusing.
Walsh, however, said that the test can work on a significantly smaller sample than most other DNA analyses.
Over time, Walsh and others in the field may isolate more traits that can be predicted from a DNA sample.
About a decade ago when Walsh started in the field, she and her mentor focused on eye color. Three years ago, she received a $1.1 million grant from the Department of Justice to expand that work.
The tool can be used not just for finding criminals but also to help identify bodies. Walsh has used it to analyze ancient remains of people. In one such study published four years ago, she confirmed that a set of bones belonged to King Richard III who died more than 500 years ago.
In the coming years, Walsh and other researchers may be able to look for additional traits in DNA samples, such as a person’s height or whether he or she had myopia.
“In five or 10 years, who knows how many traits you might provide,” Misner said.
Source: The Indianapolis Star
Information from: The Indianapolis Star, http://www.indystar.com
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