Postdoctoral Fellow Profile – Lucas Mentch


Lucas Mentch, SAMSI Postdoctoral Fellow.

Lucas Mentch was born in Indiana Pennsylvania, a town in Western Pennsylvania just east of Pittsburgh, and grew up in central Pennsylvania near Harrisburg. While he was attending high school, he took a statistics course and decided to pursue the subject at Bucknell University in Lewisburg, PA where he majored in mathematics. He asked his professors about how to pursue a career in statistics and many of them told him it was good to have a background in math first.

Lucas attended Cornell University for his graduate studies, where he obtained a Masters and PhD in statistics. He got interested in machine learning and has been looking at developing new statistical inference techniques in this context. He looks at big, messy datasets that are difficult to apply traditional statistical models to, and applies a learning algorithm to pick out large-scale patterns. Those algorithms are good for making predictions, but are difficult to use to assess the uncertainty of a prediction or where it comes from. Lucas’ research is trying to bridge the gap between machine learning and traditional statistical analysis.

While Lucas was at Cornell, he started thinking that criminology or forensics was a good area in which to try his new methods. “You’ve got either data from specific crimes or a crime database where you are trying to pick out raw patterns. You might be looking for other specific things, such as a specific time when crimes are committed, or certain areas in a city where crime occurs more often. I wanted to use machine learning to find those larger patterns, but also trying to see which variables are actually making a difference,” Lucas explained.

Lucas was alerted to the program at SAMSI by Len Stefanski, a professor at NC State and also by Benjamin Risk, another postdoc who is at SAMSI this year after finishing his degree at Cornell.  Ben is involved with the Challenges in Computational  Neuroscience program.

Lucas is involved with two working groups. He is participating in the Bias group. He remarked “There is not been a lot of attention in the area of bias in the past. It has to do with how much of a forensic examiner’s case-specific knowledge is influencing what they conclude. So, for example, if they know a lot of details about a murder, is that influencing what they say? ” The group is working with the Houston Crime Lab to set up blinding procedures where a case manager acts as an intermediary to police and the analysts. The case manager screens the information before it gets to the analysts to ensure the tests are carried out in an unbiased fashion.

The other working group that Lucas is in is trying to assess the quality of latent pattern evidence. Fingerprints are taken from a crime scene using whatever means are available and then scan it into a system to be imported as an image. But the quality of each scanner can be different, just as any piece of computer equipment or camera taking a photo can be different.  Different kinds of scanners distort the fingerprints in different kinds of ways and some scanners can produce a crisp image, even when the fingerprint itself is very smudged.

“There’s been a lot of work on quality metrics for fingerprints. So you have a fingerprint and someone puts a number on how good the fingerprint is compared to others. One of the things our group is trying to do is to say ‘does it matter what type of scanner you use with the original fingerprint?’  Our group recently got some data and can already see that fingerprints scanned with one type of scanner are almost universally better than those taken with another type of scanner according to most existing quality metrics,” Lucas said. He explained that a good scan of a bad fingerprint can often get a higher score than a good fingerprint scanned with a bad scanner. The group is well into completing this project.

“One great thing about the SAMSI program is that I have been able to meet and interact with people in forensics. Most universities don’t have a Department of Forensics, so it would have been difficult to develop these relationships in a purely academic setting,” noted Lucas.

Lucas on his motorcycle

One of Lucas’ hobbies is to ride motorcycles.

When Lucas has time to himself, he loves to ride motorcycles watch movies of all genres.

Next year Lucas will be back at the University of Pittsburgh. He took a year of leave to be able to participate in the SAMSI program.  He will continue to collaborate with people from his working groups on the projects they have started.

Op-Ed in Post-Gazette: Why Forensic Analysis of Crime Scenes is not as Reliable as you Think

SAMSI was featured in an op-ed piece in the Post-Gazette that was written by Lucas Mentch, Maria Cuellar, William C. Thompson and Clifford Spiegelman, all whom are participating in the SAMSI program on forensics this year.

The piece focuses on the Netflix mini-series, “Making a Murderer,” that raised questions about the actions and motives of law enforcement. Read their piece here.

My Experience at the Undergraduate Workshop Focusing on Forensics

The following was written by Briahnna Austin, and undergraduate student from University of California Riverside.

Briahnna Austin

Briahnna Austin

Statistics is the interchange and communication of everyday information.

This past February of 2016, I was fortunate enough to attend my first SAMSI workshop. The topic was forensic science and I was completely overjoyed and anxious, not only for the material I was going to engage in, but also excited for the interesting people I was going to interact and converse with. Coming from an undergraduate biology background, and aspiring to go into graduate level biostatistics, I have a particular fondness for interdisciplinary fields. This interdisciplinary material I was able to find during SAMSI’s Forensic Science Workshop; the purpose of this workshop was to give insight about how statistics, mathematics, data, and scientific principles amalgamate to form what we call forensic science.

Upon my arrival I was able to meet a professor from Duke at the airport; this was one of the most amazing coincidences since SAMSI has ties with Duke; I took it as a sign the workshop has something important in store for me, which it did. On the first day of the workshop, I was able to learn about comparative bullet analysis, retail sampling, and latent fingerprinting. The speakers highlighted the importance of decision-making and techniques choices. In forensic science, there is a large toolkit of information to pull from, and this toolkit gets larger as technology grows so it is our job as the statistician, investigator, or forensic scientist to make responsible and informed selections. During the first day, I was also able to see a forensics science lab; this is where movies and TV shows portray a lot of action going on, but it is different in the real world. Going to the forensic lab, gave a great opportunity to clear up assumptions and see what the real “CSI” does on a daily basis. The director of the crime lab showed my group around the facilities, and I kept hoping to see something scary or something crazy pop out of the wall, but no luck.

two lab workers

Lab workers at the Wake County Crime Lab.

During the next day of the workshop, I was able to learn about the uniqueness fallacy, statistical reliability, contextual/confirmation bias as well as a Bayesian model for fingerprint statistics. This gave insight into how important reproducibility of work as well as professionalism comes into play. In this field of work, it is essential to keep out biases and ensuring statistical reliability can assist with the types of bias we went over. The take away from both days was the idea of accountability of your work and passion for the field. Every speaker enjoyed his or her line of work. Their commitment to the field was inspiring, and shows first hand how forensic science is a collaborative effort, and when working open dialogue and communication is key to success.

Students listening to a lecture.

Students listening to a lecture.

The last large take away I acquired from this workshop was regarding networking. One of my most vivid memories during the SAMSI workshop, beside the awesome food, was communicating with the post-doc student, and undergraduate students. At the end of the first day I was able to talk to post-doc students, which help steer me in the right direction for my educational future. I am glad SAMSI provided the time to network with post-doc students; they were very friendly and funny. Not only did I network with the post-doc students, but the students attending the workshop as well. The SAMSI workshop gave me the opportunity to make new friends. Moving forward in education and career aspiration, I will be calling upon others for different aspects in STEM. Looking around the conference room and realizing these students will be the next set of forensic scientists, investigators, statisticians, and researchers, it is important we are able to network with one another. I would definitely recommend this workshop to other students and I encourage student to seek out other SAMSI opportunities as well. Lastly, do not forget to take many pictures; looking back, I realized how scenic Durham is and wish I had more pictures.