Solving a crime – the real-life way
QIAGEN’s solutions for use in forensics are increasingly helping law enforcement authorities around the world to solve an expanding range of crimes, even burglaries. A leading forensic scientist explains how forensic technologies, which have become part of our everyday culture through TV series, are being used in real life to generate insights in the fight against crime.
It may not
make the headlines, but burglary is a persistent problem for law enforcement authorities given the magnitude of lost property and the challenges to find culprits. In the U.S., for example, about two million burglaries were committed in 2013 and resulted in about $4.5 billion of property losses. In Germany, a burglary is committed every three minutes. With average clearance rates as low as 15%, authorities are turning to modern forensics solutions to help solve crimes. The ability to do so is rising as more and more DNA samples are collected at crime scenes, and from criminals, which is important given the high rate of “repeat offenders” especially in burglaries.
Trace evidence recovered from a crime scene is analyzed by professional lab technicians in highly specialized and validated laboratories operated by police agencies or private services such as Eurofins Medigenomix Forensik in Ebersberg, Germany. This laboratory, which processes several thousands of trace samples annually, generates reports known as “genetic fingerprints” that offer authorities a way to help identify suspects and confirm their involvement in a crime. Eurofins has established highly efficient and standardized workflows to handle an ever-increasing workload of crime scene samples being submitted for processing by various police authorities in Germany. The forensic review process begins with the documentation and examination of evidence that could contain human DNA. These samples can involve any materials containing DNA such as hairs, a blood stain or saliva, as well as even fingerprints that often include skin cells.
Once samples have been secured from the evidence, the next step is DNA extraction and isolation. Given the large number of samples to be processed, Eurofins uses a number of QIAsymphony automation platforms to ensure efficient handling and reliable results. “The extraction of DNA is one of the most crucial steps in the entire workflow,” says Dr. Burkhard Rolf, Director of DNA Forensic Services at Eurofins. “You need to obtain as much DNA as possible, and it has to be free of inhibitors that could contaminate the results. Losing the sample could put an entire crime investigation into jeopardy. But thanks to advances in molecular technologies, we are increasingly able to obtain sufficient amounts of DNA to generate a full genetic fingerprint, even if all we have are just a few skin cells found on a doorknob.”
“Currently, on average every third DNA profile
we create triggers a hit. I’m very confident that the likelihood of getting
positive results will further increase going forward.”
Dr.Burkhard Rolf, Director of DNA Forensic Services at Eurofins
PCR amplification and quantification
Once the DNA has been extracted, it is ready to generate the “genetic fingerprint,” which is based on the comparison of up to 24 markers – primarily so-called Short Tandem Repeats (STR) from certain areas of the human genome. To generate the genetic fingerprint, specific pre-defined parts of the extracted DNA are amplified using highly sensitive kits based on polymerase chain reaction (PCR) technology, such as QIAGEN’s Investigator ESSplex SE Plus or Investigator 24plex QS kits. Many laboratories also choose to initially evaluate whether the sample includes sufficient DNA or if there are inhibitors present that might affect the downstream analysis. “The specific set of genetic markers used for this process, which is very effective even in large populations, may differ between various countries, but we see a global trend toward harmonization to facilitate the exchange of data across borders,” says Dr. Rolf.
In the final step of the workflow, the exact lengths of amplified DNA sequences are measured using a “capillary electrophoresis” sequencing instrument. “In the end, when we are assessing whether a suspect’s DNA matches what was found at a crime scene, it comes down to looking at the variability in the length of the analyzed markers. These lengths differ significantly between humans, so a match means there is a confirmation, or ability to identify an individual. Based on the current markers sets, the chances of someone else having the same DNA profile as you are as high as 1 in 1 trillion, or even higher, and that is a 1 with 12 zeros,” says Dr. Rolf.
Analysis and reporting
Following a final review by Dr. Rolf, a DNA profile report is sent to the law enforcement agency that submitted the crime scene samples for processing. It is the responsibility of this agency to compare the results with data stored in national DNA databases with the hopes of finding a match. “Currently, on average every third DNA profile we create triggers a hit”, says Dr. Rolf. “I’m very confident that the likelihood of getting positive results will further increase going forward, not only due to the growth of the databases but also due to novel applications being developed, such as the ability to determine certain physical characteristics of a suspect based on DNA found at a crime scene. This might still not live up to what you see in crime shows on TV, but it will enable us and other laboratories to generate new insights to help win the fight against crime.”
QIAGEN’s product offering
QIAGEN is the global leader in sample technologies in human identification and forensics and is already successfully commercializing STR kits in different regions of the world. With around 400 accredited forensic crime laboratories analyzing more than four million casework and reference samples per year, the United States is by far the largest market for human identification and forensics. This year’s launched Investigator STR kits comply with the latest U.S. requirements that labs must implement expanded marker sets by 2017 as part of an FBI upgrade of CODIS (Combined DNA Index System), as well as complying with European and Interpol standards. Following the introduction of these new standards, QIAGEN is the first new entrant in more than 20 years in the U.S. market for STR test kits. Both new kits - the Investigator 24plex QS Kit and the Investigator 24plex GO! Kit – got listed by the FBI as frequently used PCR kits accepted for the National DNA Index System now, which was a big milestone for the company.
Overall QIAGEN’s solutions cover the entire field of forensic analysis from DNA extraction to final results. These include special products for the extraction of genetic information even from demanding test materials, novel techniques for quality control of isolated nucleic acids, and numerous testing methods that cover different forensic marker sets and the appropriate equipment for automating such procedures, which also helps minimize human error. Find out more at https://www.qiagen.com/us/products/human-identity-and-forensics/