It's not always easy to identify blood correctly in a scene of crime.
This was the case of a murder trial that Bruce McCord, a forensic scientist at the International University of Florida, served as a witness expert. A woman was murdered shortly after divorce and DNA from her former husband. But it was hard to tell if DNA was the result of innocent contact between the two, or if it was incriminating, and it came from the blood.
"The techniques we need to detect blood are not as sensitive," says McCord. When the test was completed, he tried to find a better method. "There should be DNA markers that could differentiate one type from another."
McCord's research on this question is part of the field of forensic epigenetics, which uses the markers located above the DNA and modifies its expression rather than the genetic sequence to collect information that could help identify a suspected of a crime. Criminal scientists and law enforcement agencies around the world believe that epigenetic leverage can add key tools to the research arsenal. They are working to develop methods that use this field of study to recognize not only the type of DNA tissue that may have been left behind in a scene of crime but the age and lifestyle of the person who left it there.
Research is still ongoing and technology needs to be tested and validated to ensure it is effective and accurate. And as science moves forward, as with any new tool that includes genetic information, its ethical concerns must be carefully considered.
"It's a fast-growing sector," says Atina Vidakis, a postdoctoral researcher studying the forensic epigenetics at the Erasmus University Medical Center in the Netherlands. "We need to understand the challenges that come with the investigation of epigenetic indicators and understand what we can do and what we can not do."
Crime Scene Science
All the cells in the body have the same DNA sequence and this distinct sequence remains constant over a person's lifetime. However, how these genes work – which proteins produce, in what amounts and when – is what is known as gene expression and changes, from the body part to the body part and in response to any kind of environmental factors.
For example, blood cells have a different purpose in the body than skin cells, so different proteins will appear in unique patterns in both cells to help them perform their specific tasks.
By identifying these patterns, it is possible to distinguish between DNA derived from the blood and genetic coding that originated from the skin, says McCord. This strategy, he says, has advantages over current body fluid identification protocols, including that it can be done with the DNA sequencing technology already in place in many forensic laboratories.
It would be particularly useful how, for example, we analyze the coatings collected in a rape kit, says McCord. "If you find male DNA, for example, there is another question whether it is from a skin cell or a sperm cell." The use of epigenetics is a more effective way of approaching this question, "he says. , fluid identification tools could also help determine whether the DNA found in a victim came from the skin or from blood or sperm.
McCord and his team work with the San Francisco police station to begin validating their methods.
Epigenetic markers are useful not only for the determination of the cell type. They also change with cell age and the latest research shows that some sets of indicators can be used to predict age within three or four years (above or below) of the actual chronological age of an individual. This quarter-four-year buffer is because the way in which the age of our cells varies among individuals. "Predicting age is really exciting for people in law enforcement," says Vidaki.
Moving forward, epigenetics could also help to predict whether a suspect is a smoker, a heavy drinker or even what his diet is. All of these behaviors leave traces and it may be possible to predict, for example, whether a person is a long-term vegetarian looking at his offspring.
"When someone leaves a sample back to a violent crime, it makes sense to try it and learn as much as possible about that person," says McCord.
Information is not enough to identify a single person – epigenetic markers are not fingerprints and there are many scientists who are not yet aware of gene expression. But knowing the age patterns and lifestyle habits of the person they are looking for can help law enforcement officers limit a suspect tank in cases where there is no DNA matching in a database.
Research is moving quickly, but scientists have noticed that they are still working to understand the limits of the methodology: Still working on samples of DNA that have been somewhat degraded or present only in small quantities? They must also ensure that methods are as effective in all ethnic groups and that age markers are equally accurate when analyzed from the blood as when analyzed by the skin. "There is a list of challenges that restrict what we can do and emphasize what we need to do to move on to the field," says Vidaki.
In May, a Polish research team published a letter in the Trends in Genetics magazine stating that the epigenetic markers they use to predict age could be used for another purpose: to determine that a DNA sample originates from someone with a formula leukemia. This has raised a basic moral concern – the indicators used by scientists to determine age or type of tissue could also possibly include sensitive medical information.
"When we do forensic analysis, we are able to take these additional symptomatic findings," says Bram Bekaert, professor of forensic biomedical sciences at the Katholieke Universiteit Leuven in Belgium. It will be important, therefore, for scientists and policy-makers to decide how much data they will get during an analysis, he says. "There must be a debate about what we can do and what we can not do."
Epigenetic markers shift with disease in a way that genetic sequences do not, which makes this moral issue specific to these methods. However, many of the questions in this field are similar to those of genetic information in general, says Matthias Weinroth, who studies ethics and biotechnology policy at the University of Newcastle. "My usual concerns are how reliable technology is and how useful it is," he says. "And how will the information be collected and used? How will it be saved?"
As police officers begin to take their hands on epigenetic tools, it will also be important to fully understand the limitations of the data they collect and how they can really tell them. "When you say it is a scientific method, people sometimes think it is objective and absolutely reliable, but everything is subject to interpretation," says Weinroth. "Truth is not in DNA."
Lifestyle information that can be collected with the epigenetic also adds a moral wrinkle, and it is important to determine how the collected data is to be distributed and to whom it says. As with all information, scientists, law enforcement and policy-makers should weigh the benefits of using data over privacy concerns.
These are the types of questions that the various stakeholders have to fight, as the sector continues to grow, says Weinroth. "It is too late to take into account the ethical and ethical aspects of a technology when it is already on the market. We need to deal with it as it emerge."