Killers and crooks, clean up after yourselves.
Scientists appear to be on the cusp of being able to develop physical descriptions of criminal suspects based on an analysis of the DNA left behind at a crime scene.
The latest breakthrough in this emerging field, known as forensic phenotyping, came just a few weeks ago when a group of Dutch scientists announced they had devised a test that allows them to reliably predict someone's age -- to within nine years -- based merely on a blood sample.
That same group has previously said it can also predict eye colour using similar methods. Hair colour is next up on the research agenda.
The scientists say their findings could help investigators narrow down the search for suspects and revive "cold" cases where there are no eyewitnesses, or where DNA from the crime scene doesn't match any profiles already stored in criminal databases.
"Our approach is expected to provide investigative leads in criminal cases by allowing an accurate estimation of the generation age of unknown individuals from minute blood stains," the team, based at University Medical Centre Rotterdam, wrote in the journal Current Biology.
"Our approach is also expected to be applied to disaster-victim identification where body parts [containing blood] are available and where age information can be crucial for final identification."
Mark Shriver, an associate professor of genetics and anthropology at Penn State University, said Friday analysis of DNA sequences can also yield clues about a someone's genetic ancestry, skin pigmentation -- even facial geometry.
A genetic-testing company he's worked with in Florida was credited with helping authorities home in on a suspect in a series of rapes and killings in Louisiana. Police had initially been led to believe the suspect was white and collected DNA samples from more than 700 Caucasian men.
But the Florida company tested DNA recovered from one of the crime scenes and determined the suspect was probably 85 per cent sub-Saharan African and 15 per cent native American.
"They are pieces of the puzzle that can direct their investigation," Shriver said.
"It may be bet ter than an eyewitness."
But some experts say the research also raises a number of legal and ethical questions that are only beginning to be considered.
Paul Wilson, Canada research chair in DNA profiling and forensics at Trent University in Peterborough, Ont., said he wonders if degradation of a DNA sample at a crime scene could lead to skewed predictions of a suspect's age or other traits.
"My first inclination is to ask: What are the technical limitations? Can you generate false results?" he said.
Secondly, he wonders if there might be occasions when information contained in a DNA-generated suspect profile might be beneficial to criminal defence lawyers. What happens, for instance, if the person apprehended has blond hair but the original DNA testing suggested the suspect would have brown hair?
"It can be helpful in one stage and a liability in another stage," he said.
A research paper prepared last year by the Library of Parliament noted that "one concern that has been raised about such methods is that the results could be used to justify 'DNA dragnets' -- the collection of DNA samples from large groups of people -- based on physical descriptions or race, whether or not there is any other reason to suspect them of the crime."
Some bio-ethicists have also raised concerns about how far the genetic testing should go.
It is not inconceivable, they say, that scientists could develop DNA tests that not only predict someone's physical traits, but also their behavioural traits, such as their likelihood for aggression or being a smoker, or their susceptibility to disease.
Privacy is also a concern, said Anita Ho, a University of B.C. philosophy professor and a specialist in bioethics.
She offered this hypothetical scenario: She happens by a crime scene and a piece of her hair falls into that crime scene.
Investigators develop a detailed suspect profile based on her DNA. Ultimately, she's cleared of any wrongdoing. But what happens now to that profile they've generated? Is it stored somewhere? And who has access to it?
By Douglas Quan, Vancouver Sun