Crime Investigation: Catching criminals- one cell at a time

DNA evidence has been used to help solve many serious crimes but until now has been limited in capability.

December 17, 2010 16:35
4 minute read.
DNA from single strand of hair

DNA 311. (photo credit: Courtesy)

A new breakthrough in DNA forensic crime scene techniques is set to enable detectives to identify the presence of a specific suspect at a crime scene even if the individual’s DNA is mixed up with that of other people who were present – a capacity that has, up to now, eluded police.

Prof. Ariel Darvasi, of the Hebrew University’s Department of Genetics, together with his student, Lev Voskoboinik, of the police forensic biology laboratory, jointly developed the technique, and recently published their finding in Forensic Science International: Genetics.

“In recent years, DNA forensics has become a very important part of police work, and it has become routine. But under today’s conditions, when DNA from multiple individuals was found at a crime scene, the evidence was cast aside and not used, and other forms of forensics were examined,” Darvasi told The Jerusalem Post on Tuesday.

In such cases, forensic officers have to try to identify suspects through other means, such as bloodstains, footprints, fingerprints or unusual items left behind.

Yet by throwing away the DNA evidence, the investigators are also disregarding a suspect’s DNA, Darvasi said.

“Our technology provides a solution to this problem. If a crime scene contains mixed strands of intertwined DNA, police will be able to see if a certain suspect was there and isolate his DNA fingerprint in the DNA mixture. This is new for police in Israel and everywhere in the world,” he added.

One example of a complex crime scene finding that has so far evaded DNA analysis is a handgun held by several individuals, including a shooting suspect.

“On the gun’s handle, the DNA of a few people will appear. Until today, police could not tell if the suspect’s DNA was present. But our technology will allow, with almost full certainty, police to identify if a suspect was holding the gun or not,” Darvasi said.

He stressed that it will take some time before the breakthrough becomes an applicable technique.

“We will have to adapt it for police use. It is like medicine. There are many stages before the final product. We also have to make sure that the evidence will be admissible in court,” he explained.

Darvasi said the police forensics department, headed by Lt.-Cmdr. Avi Domb, was fully updated about the results of the research and “very happy” about the breakthrough, adding that the two sides were working together to forge a way to make the science applicable.

RECENTLY, DNA evidence has been used to help solve many serious crimes, from the choking to death of a seven-year-old in Bnei Ayish by twin brothers Naor and Adi Sodmi in January, to the sexual assault on a woman by Erez Efrati, former bodyguard of the chief of General Staff last year.

DNA evidence was also crucial in the arrest of Dimitry Kirlik for the murder of six members of the Oshrenko family in Rishon Lezion in 2009.

A DNA sample taken from clothes left at the murder scene by Kirlik was compared with a DNA sample taken from Kirlik’s car, which officers had discreetly broken into as it sat in a parking lot in Eilat. The perfect match which followed allowed officers to place Kirilik in the apartment.

Yet the development was only a small step in the DNA-linked developments scientists expect to take place in the coming years.

In the police forensics world, such progress will one day mean that crime scene investigators will be able to construct a visual profile of a suspect purely from bits of DNA he or she left behind.

“I think we are at the start of a genetic revolution,” Darvasi remarked. “Today we have the tools to decode what every gene does, and the impact on medicine will be all encompassing. But this process is not like the French Revolution in terms of time. We are talking about many years.

“In terms of forensics, the genetic revolution is happening now. We can identify suspects using their DNA. In the future, we will be able to get information from DNA evidence that will allow us to identify a suspect even if he is not on a preexisting database.”

Currently, biological findings such as DNA and fingerprints are run through a police database to see if any matches come up. If none are found, they are stored for a time when a suspect is arrested, and can be used to corroborate or dismantle suspicions against a suspect.

Forensic officers can now know the color of a suspect’s eyes and skin tone from DNA left at a crime scene, but to a minor extent.

“Once you can take fuller visual details, a full profile can be constructed. But we are very far from that point,” Darvasi said.

Yissum, the technology transfer company of the Hebrew University, has registered the new technique as a patent, and says it is currently seeking a partner for further development of the technology into a product.

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