The weight of evidence: New Mexico Department of Public Safety Forensic Laboratory DNA Unit focuses on science, precision, while managing pressure, stress

Work within the DNA Unit of the New Mexico Department of Public Safety's Forensic Laboratory in Santa Fe can be highly challenging and not just in a scientific way. There's a mental health aspect to the job that many have experienced including Roslynd Archuleta, DNA supervisor and 18-year forensic scientist.

Archuleta managed the largest case to ever come through the DNA Unit, with more than 300 pieces of evidence, 13 reports and over two years of work in the Victoria Martens case.

"It was very gruesome, high profile and a very stressful case to work," said Archuleta who is also the Combined DNA Index System Administrator. "The case was really important; and testifying was critical. Also, it was important for me to highlight the impact of our work on us as forensic scientists. We need to focus on mental health and ensure our analysts are taking care of themselves. We work with really heavy information, and that can really eat at you, especially when you have a case like this one that involved a child. I had young children myself at the time, and a lot of the items I was seeing in the case were items I had at home for my own children. That hits really hard as a scientist realizing that the work you are doing - that there was a child that was hurt.

"I try to be a big advocate for all of us to take care of our mental health - to get help. I got some PTSD from it. I'm pretty open to talking about it. I found a therapist which was critical to find a better ground to stand on after such a difficult case."

Roslynd Archuleta, DNA supervisor.

The 'high-profile' Martens case came with significant stress and pressure, according to Archuleta. In addition to the physical evidence she examined, she also reviewed images submitted by the agencies for testing purposes.

"The items that I had to test were very clearly indicative of how brutal it actually was," she said. "It felt like it was literally in my face at every turn - it became very prevalent. There was no getting away from it. I didn't want to see any coverage because I didn't want it to bias me, so it became this big challenge of how do I maneuver every day and try to avoid seeing any coverage while also coping with the other things that I had seen in this case. It was very difficult."

While this was the largest case ever, the challenges associated with positions in the DNA Unit are not uncommon. According to Archuleta and DNA Technical Leader Jennifer Otto, their work involves a great deal more than processing DNA results. DNA analysts often work multiple cases at once and travel across the state to testify in court.

In her role, Otto said other duties include training new analysts, validating and implementing new procedures to be used for samples, conducting quality assurance activities, outsourcing of cases when necessary and managing the Sexual Assault Kit Initiative program.

DNA Technical Leader Jennifer Otto.

In the DNA testing process, each piece of evidence is examined individually, with known samples handled last to minimize the risk of contamination. Many items first undergo serological testing to identify the possible presence of body fluids such as blood, semen or saliva. A sample for DNA analysis is then collected.

The DNA is then extracted by breaking open the cells in the sample (using a Promega Maxwell RSC). After that, the amount of DNA is measured (quantification using a 7500 Real-time PCR instrument). The DNA is then copied many times (amplification using a Thermal-Cycler) and labeled so it can be detected.

Next, the DNA is analyzed by a machine (a genetic analyzer) that reads it and produces a DNA profile. The same process is applied to known samples, allowing the profiles to be compared to determine whether someone may be included or excluded as a match.

As far as types of DNA that can be tested, virtually anything that comes from the body can be examined. While most people think of saliva, blood or semen; hair roots and skin cells can also be tested.

Tyler Griffith, forensic scientist in the process of setting up an amplification plate.

"Often at a crime scene, we're going to run into a situation where there's a lot of blood and blood is a very good source of DNA," said Archuleta, who has a bachelor's degree in biology from New Mexico Tech. "Blood is a very robust and reliable form of being able to obtain a DNA profile. We can also get a good amount of DNA from saliva. Oftentimes we'll have sexual assault kits in which there may be semen present. That's also a very good source of DNA. We can obtain DNA from hair, although that becomes a little bit more tricky because we're not obtaining DNA from the hair itself, but from the tissue around the root of the hair - so we have to perform a microscopic examination to determine whether or not there is enough tissue around the root of the hair to be tested."

"Skin cells can be transferred through everyday contact - such as shaking hands, touching a phone, or handling objects," said Otto who received her master's degree in forensic genetics from the University of North Texas Health Science Center. "Human skin naturally and continuously sheds cells as part of a normal biological process. Because of this, items that are frequently handled - especially those with textured surfaces, can collect these shed skin cells. For example, regularly holding an object with a grip, like a firearm or steering wheel, may result in skin cells being deposited onto those surfaces. This category of DNA can run the gamut from having a lot of DNA and being close to something like blood or saliva to having almost no DNA."

Forensic Scientist Eve Tokuaru prepares a 96-well plate for amplification.

Preservation of the DNA prior to the lab receiving it can play a big role in the outcome, according to Archuleta whose father was a Santa Fe Police Department detective and mother was in medical testing. If the evidence was exposed to UV light or moisture, that could impact the item.

"There's a lot of factors that play into DNA recovery," said Otto. "We try to give guidelines on storing DNA evidence, including packaging in paper rather than plastic and avoiding extreme environmental conditions particularly heat or light, so there's no urgency because of potential breakdown."

Sometimes items collected for DNA samples appear obvious like a blood stain for example, but often items collected don't necessarily have any known DNA, but it can still be an important step for law enforcement attempting to solve a crime.

Analyst Emily Speer prepares tubes for DNA samples.

"We're always going to suggest they collect it if they are not sure," said Archuleta. "You can't always go back to collect evidence later."

Often, law enforcement does not have a suspect or enough evidence to collect a DNA sample. In these cases, DNA profiles from evidence are entered into the Combined DNA Index System, a database used to generate investigative leads.

The Combined DNA Index System is strictly regulated and includes profiles from suspected offenders or arrestees - not victims or elimination samples. Most profiles entered are unknown and continuously compared against others in the database.

If a match is found, the person's identity is provided to law enforcement, who can then obtain a DNA sample with a warrant. That sample is tested separately, and a formal comparison is made to confirm whether it matches the evidence.

Analyst Justin Rabe examines slides on the microscope.

In a typical year, the DNA Unit processes over a thousand cases with thousands of samples with a team of 14 analysts. Evidence samples collected can vary from cookies, candy bars, pizza, sandwiches, bitten off tip of a nose or other body part, cigarette butts, drinking containers (all which someone would have put their mouth on or taken a bite and the lab can swab the area for saliva), knives, swords, clothing, a moldy shoe, pillows, bedding and even curtains with blood on it.

As they process those samples, each analyst must take specific steps to ensure the DNA isn't contaminated.

"We have the extra level of trying to minimize contamination in our unit," said Otto. "Because we're dealing with DNA evidence, and we contain DNA ourselves, there are a lot of extra precautions and steps that we take in our unit to minimize the potential for contamination in the laboratory so that the results we are reporting are the actual results from that piece of evidence."

These actions include wearing lab coats, gloves and face masks and using bleach where necessary to clean work areas - with the intent to essentially destroy the unwanted DNA.

Analyst Minuet Whitney performs serology testing on evidence items.

Sometimes in their work, obtaining results can be a surprise.

"I had a sexual assault kit that involved the use of a stick and I remember being kind of skeptical as to whether or not I'd be able to obtain anything, because it's a difficult item to swab due to the surface being really porous," said Archuleta. "I remember having to really look very closely and I did see one area that seemed like maybe there was some shiny staining on it. So I tested it, and I remember getting a full profile, not thinking that I would get a full profile. To my recollection it corroborated the circumstances of the case. It was helpful that I found the profile where and when I did. With items like that that, you're really not sure whether or not you can get anything from it - sometimes it just surprises you."

An analyst sets up a quantification plate.

As the DNA Unit moves into the future, they are working to implement a software program called STRmix, a type of probabilistic genotyping tool that helps analyze complex DNA evidence, according to Otto. Unlike current methods that simply determine whether a person is included or excluded, this software uses computer modeling to better interpret mixed DNA samples - especially those with multiple contributors. It can estimate how likely it is that someone's DNA is present and help separate overlapping profiles, potentially allowing analysts to draw more detailed and accurate conclusions from evidence that was previously too complicated to interpret. The system has already been validated, and the lab is now training staff and preparing procedures for its use.

"As we move into the future seeing the next generation of analysts come in and be invested in what we're doing, eager to do the work - my hope is we'll leave it in good hands when we're done," said Otto.

"One of the things that makes me excited in every case I work, is that even though a lot of the steps are the same, every case is very different," said Archuleta. "You have to think outside of the box. You have to pull different pieces of information together and when you get to that final DNA profile, it's like you're solving your piece of the puzzle and that can solve a bigger puzzle about what happened in the case. You just really never know what's going to happen."

The DNA Unit - from left to right, from the top down: Noah Schafnitz, Justin Rabe, Tyler Griffith, Kayla Lopez, Jordan Weisend, Emily Speer, Minuet Whitney, Roslynd Archuleta, Soledad Negrete, Jennifer Otto, Ashley Baines, Brianna Bermudez, Cecilia Torres-Martinez, Eve Tokumaru.

For state employees looking for a therapist, the Employee Assistance Program can help with services available 24/7. Call 833-515-0771.

Story by New Mexico Department of Public Safety Public Information Officer John Heil. Photos by DPS Media Relations Unit - Payton Santillanes.