An Interview with a Y-STR Analysis “Rockstar”
Dr. Lutz Roewer
Interview Written and Condensed by Ann MacPhetridge, Promega
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Dr. Lutz Roewer is one of the renowned forensic scientists who transformed DNA forensics through studying the Y-chromosome and demonstrating the value of Y-STR analysis for forensic casework. The use of a YSTR profile can help by excluding male suspects, or indicating multiple male contributors, or provide information that can be used to help find an unknown male perpetrator. Additionally, YSTR analysis is done for kinship testing and cases such as missing persons or for identification of victims in mass disasters.
Dr. Roewer is currently an Associate Professor for Forensic Genetics at the Institute of Legal Medicine, Humboldt-University Berlin (Germany) and Director of the Department of Forensic Genetics at this institute.
In addition to his work as a professor and researcher, Dr. Roewer, along with Sascha Willuweit at the Institute of Legal Medicine and Forensic Sciences, Charité – Universitätsmedizin Berlin, organizes and manages the Y Chromosome Haplotype Reference Database (YHRD).
Launched in 1999, the database has grown steadily over the past 20 years as more laboratories submitted their haplotypes. As of June 2019, more than 285,000 haplotypes from 1,308 sampling locations in 135 countries were submitted by more than 450 institutes and laboratories worldwide. In geographic terms, about 47% of the YHRD samples are from Asia, 23% from Europe, 11% from Latin America, 14% from North America, 3% from Africa, 1% from Oceania and less than 1% from the Arctic. The YHRD was reorganized in August 2014 in order to reflect Y‐specific metapopulation structures (MP). Contributors to the YHRD are requested to provide metadata (geographic coordinates, ethnic ancestry and language group) on their population samples in order to assign these sensibly to an MP. In June 2019, the US Y-STR Database was discontinued, and the database was permanently transferred to the YHRD. Additionally, forensic science providers in countries like UK or Singapore transferred their national YSTR databases to the YHRD platform. Because of the international makeup of YHRD, this allows interpretation of Y‐STR results in a population‐based context, a new approach to using Y-STR data as investigative tools.
I had the pleasure of interviewing Dr. Roewer while attending Promega’s 20th European Forensic DNA Working Group Meeting in Hamburg, Germany in November 2019.
I’ve known you for a while, but for our viewers, can you tell us a little more about you and the work that you are doing?
I am what we call a forensic geneticist. I work in Berlin in the University Hospital in the Institute of Legal Medicine and Forensic Sciences. I joined this institute very early in 1987, and today I work as a contract lab for the Berlin Police—we do casework—large numbers of samples. Secondly, I am a professor in Forensic Genetics so I do teaching and research with larger projects.
What inspired you to go into Forensics?
After my studies I had a really big chance to join the Institute of Legal Medicine in Berlin which is a very famous institute. The Institute combines the work for the courts with a lot of research, so as a young assistant scientist, I was given a chance to do DNA analysis in the early years. It was invented in 1986 and we started in 1987. So this attracted me enormously and was a really big chance. Our director was charismatic, and he offered me a world of chances so I had no doubt that forensic science, forensic genetics was something that I could do for the next decades.
And so you have…the rest is history. What are you most excited about for the future of forensics? We’re hearing a lot this week about new technologies and new applications, but what are you most excited about personally?
I would say the development of DNA from a pure evidence to an investigative tool, that is what I think we currently see. It is a long way, hard way, with technical challenges but also other challenges, legal challenges, procedural challenges but I think this is the most exciting to have DNA early on as an investigation tool for the police.
I consider you a Rockstar of Y-STRS. You have a list of accomplishments that is quite long. Are there 2-3 that you are most proud of that you’d like to share?
By chance, we cloned the first STR on the Y-chromosome and we used it in the first year in a rape and murder case and someone who was innocent was released from jail. This was my start with the Y-chromosome. And of course, the 2nd big thing was to organize “out of the box” workshops without any big companies or societies behind. So we organized it simply for the sake of sharing the technique. This was the middle of the 90s. From these workshops a database arose, which is now well known, it is the YHRD. It is a large reservoir of data from scientists working in forensic labs, now at more than 300 labs, and they share data. And I think this is the spirit which we created in the middle of the 90s. And maybe it was the time which allowed it, which is today more difficult. Because of this spirit, I’m proud of that.
It’s quite the legacy. There have to have been some challenges as well. What were some of the biggest challenges that you had to overcome in the field?
Currently we have a challenge to balance DNA as an investigative tool with privacy issues, and the needs of police investigations. The process to get in touch with lawmakers and with policy makers is very challenging and sometimes very frustrating. This is not my personal project, but it’s many people working in the field are involved somehow in the discussion. We see what the policy and lawmakers are doing and we see what is needed. This process at least at the beginning is kind of frustrating and challenging.
Absolutely, I think this is a global issue. My last question for you is, can you share a little bit of what you’ll be presenting on this morning?
For years we have been interested in constructing and reconstructing the ancestry of an unknown DNA donor. For the police I think it is very important the geographic affiliation of a person. This is very interesting because it touches fields like evolutional biology, anthropology, population genetics and so on. So I try to present 3 cases in a time span between 2002 and 2019. Out of dozens of cases, I present three which I try to illustrate how complicated this reconstruction of ancestry is, but also how helpful it could be for the police. One case is about a skeletonized baby corpse found in wood in Southern Germany; here we could help to confirm the father’s identity. This was the first case ever in Germany, where biogeographic ancestry was admitted as evidence at a German court. In another recent case a body of an adult male was found, a victim of brutal murder. We found that the ancestors of this victim lived most probably in the Southeast of Europe. And in the third case, already from 2002, and interesting because a court ordered the biogeographical analyses, we could deliver information on a suspect in an attempted murder case in Berlin. Our Y chromosome analyses point to the South of Europe, and indeed the man was identified and arrested. He was Italian. The current German law restricts the use of these methods for the identification of unknown corpses whereas in other jurisdictions also DNA traces left by a suspect could be analyzed using forensic intelligence.
Thank you so much for taking the time out today—I’m really looking forward to your presentation!
To learn more about Promega’s European Forensic DNA Working Group Meeting, contact Nicole Siffling.
¹Kayser, M. Forensic use of Y-chromosome DNA: a general overview. Hum Genet. 2017;136(5):621–635. doi:10.1007/s00439-017-1776-9
²Roewer, L. Y‐chromosome short tandem repeats in forensics—Sexing, profiling, and matching male DNA. WIREs Forensic Sci. 2019; 1:e1336.