Interview: Clearing DNA Backlogs

A look at a laboratory that cleared its DNA backlog
and increased throughput in just a few short years

An exclusive Evidence Technology Magazine interview with

Joe Minor
Technical DNA Manager & Special Agent-Forensic Scientist Supervisor
Tennessee Bureau of Investigation—Nashville, Tennessee

In 2005, the Tennessee Bureau of Investigation (TBI) DNA lab—like many laboratories across the country—was experiencing a backlog of unanalyzed DNA samples from criminal cases. Carrying out an initiative spearheaded by Joe Minor and funded by grants from the National Institute of Justice, the TBI was able to efficiently reduce its backlog and increase its throughput. Today, Tennessee’s central laboratory in Nashville and its two regional laboratories in Knoxville and Memphis have been said to have some of the fastest turnaround times in the country. Minor shared some of the strategies used to accomplish this backlog reduction, as well as some tips for working with your state laboratory to ensure good DNA-testing results.

EVIDENCE TECHNOLOGY: Can you tell us a little bit about your laboratory’s efforts to reduce its DNA backlog?


MINOR: We were interested in reducing our turnaround time. We got started around the end of 2005. Utilizing grant money from the National Institute of Justice (NIJ), we took a four-pronged approach that resulted in decreased turnaround time and dramatically increased throughput.

EVIDENCE TECHNOLOGY: What was the first step in this four-pronged approach?

MINOR: First, we used some of the grant funding to outsource about 900 cases. That took some of the casework off of our plate and allowed an external lab to do the DNA typing. They would send back the results to us for review before we issued reports.
EVIDENCE TECHNOLOGY: What was the second step?

MINOR: The second thing we did was provide overtime funds for casework. We also used grant funds for that. Overtime is a blessing and a curse, of course. If you love it, you can use a lot of overtime and earn extra pay, and it certainly has an impact on getting more cases out. So some people were able to stay later, sometimes come in on Saturdays, and work toward getting that backlog down.

EVIDENCE TECHNOLOGY: What other areas did you focus on to decrease the DNA backlog?

MINOR: We also used that grant money to purchase instrumentation that allowed us to increase our capacity and efficiency. Some of those instruments included extraction robots, which cut down the time it takes to extract DNA from samples. We bought some real-time PCR quantitation devices, which are more accurate and faster than the procedure that most DNA laboratories were previously using. We bought some additional thermocyclers—instruments that aid in the amplification of our DNA samples. And then we bought some more genetic analyzers. The genetic analyzers are the workhorse of a DNA laboratory. The end-product of the amplified DNA goes in that, and that is where your profile comes out. So if you have more analyzers, obviously you get more cases done.

EVIDENCE TECHNOLOGY: And what was the fourth part of the effort?

MINOR: We had Applied Biosystems validate some of our new instrumentation and chemistries. Before this, we had to stop what we were doing in order to validate the instruments—and that was something we just did not have time for back then (in 2005 through 2007) when our Nashville laboratory was looking at a 24- to 26-week turnaround time. So using an outside company for instrument validation freed up valuable time to work on cases.

EVIDENCE TECHNOLOGY: Did overtime provide enough manpower, or did you need to hire additional analysts?

MINOR: Yes, the director of the TBI was able to obtain six more scientist positions. That, of course, really had an impact on the number of cases we were able to handle.

EVIDENCE TECHNOLOGY: You said the lab faced a 24- to 26-week turnaround before this overhaul of your DNA laboratory workflow. What is your expected turnaround time now?

MINOR: We now have about an eight-week turnaround.

EVIDENCE TECHNOLOGY: That’s an impressive reduction! What kinds of numbers are you seeing with your casework now?

MINOR: At our Nashville laboratory, we generally get in about 100 cases each month, and we get out about 100 each month. In the regional labs, which are a little bit smaller than the main lab, it is probably about 40 in, 40 out.

EVIDENCE TECHNOLOGY: How much has your throughput increased?

MINOR: The number of DNA samples that we processed at all three labs more than doubled between 2006 and 2008. We processed 2,500 samples in 2006. We processed 5,600 samples in 2008. And based on where we are right now, I think it is probably going to get up to about 6,000 samples in 2009. All of the changes we made definitely helped us process more DNA samples, got our turnaround time down, and a great thing about it—other than the new positions, which have to be funded by the state—most of the other equipment and overtime efforts were funded by the NIJ. That was quite helpful to our agency.

EVIDENCE TECHNOLOGY: Was it difficult to obtain that NIJ funding?

MINOR: The NIJ has been putting out grants on a yearly basis. The solicitations usually come out in the spring. So what you have to do is submit a proposal and define exactly what you want to use the money for. Once you write up the abstract and the narratives and a budget proposal, it goes to NIJ and (hopefully) they approve it. That process does not take very long—the Federal year starts in October, so if you put in an application in May, you should know something by September.

EVIDENCE TECHNOLOGY: It sounds like it was well worth the time and trouble to apply for that grant money.

MINOR: Certainly. It has been a great program for the whole country. It has definitely had a major impact. And with the way the economy is now, we are thankful to still have those grant funds in place.

EVIDENCE TECHNOLOGY: What advice would you give a laboratory manager who is looking to reduce backlogs and increase throughput?

MINOR: Make sure your analysts get up-to-date training for the emerging technologies and instrumentation. It is constantly changing. When the analysts go to the meetings and see some of the instrumentation—such as robotics, for example—they are going to come away understanding it. They are going to know how to come back and apply that to our casework and determine whether it would help our lab and actually increase our throughput. New instruments come out about every four or five years. So, I would advise you to make sure your analysts are up to date on that technology.

EVIDENCE TECHNOLOGY: Do you have any other advice?

MINOR: Be aware that with an increase in throughput there will be an associated increase in costs. So when you get your backlog and turnaround time down, remember that you are also increasing the number of samples you work—and that is going to cost more money. In one year, our supply contract went from $250,000 to $500,000. Which makes sense, because we are doubling the samples that we process.

EVIDENCE TECHNOLOGY: Your throughput has increased because of changes your laboratory made to its workflow. But do you think you have also seen an increase in throughput due to an increase in samples coming in from crime scenes?

MINOR: In short—Yes. We are working more cases. But when you really start to look at that data, you see that we are also getting more DNA requests for additional items per case. And I am sure it is the same way in other laboratories across the country.

EVIDENCE TECHNOLOGY: Is there anything that investigators and people working the crime scenes can do to help the DNA analysts be more efficient?

MINOR: It is all about communication and collaboration. We want to hear from the agencies. Anything you can tell us about a crime scene is definitely helpful. Include detailed written reports along with the samples you submit. We also encourage telephone calls back and forth where we can talk about certain items that may have a higher priority than others. We want to get the facts of the case, and we want to know what question the investigator wants answered. If we can answer the question by analyzing just a few samples—in other words, if we can avoid doing 20 exhibits that all provide the same profile—then we can move on to the next case and we can do more cases overall.

EVIDENCE TECHNOLOGY: But how do you know for sure when you have answered that question?

MINOR: Well, sometimes you don’t know. And if a case is negative, we certainly are not suggesting that we will only work 20 exhibits and then stop, no matter what. That is not what we are saying. Because if you don’t get a profile from the first 20 exhibits, you keep looking at the others until you find something—even if it takes you every piece of evidence out there.

EVIDENCE TECHNOLOGY: So give me an example…

MINOR: Let’s say there is a sexual assault case. And the analyst looks at the vaginal swab, finds sperm, extracts it, and it matches the suspect. The question the investigator was asking was, “Who did this?” Well, you have already answered that question. Just to be safe, there may be an article of clothing that you want to look at. But do you need to look at ten items of clothing, bed sheets, and everything else? No. Because every time you do that—besides costing money—you are taking up time where you could be moving on to the next case. And that is something that I think all laboratories are looking at.

EVIDENCE TECHNOLOGY: When you teach classes for crime-scene investigators, what are some of the key points in DNA collection that you cover?

MINOR: I talk to them about basic concepts, like proper recognition and preservation of the evidence. We discuss the fundamentals of packaging biological evidence and how that should be packaged in breathable containers. And everything needs to be packaged separately. Even if they think that it is the victim’s clothes and it is all the victim’s blood and it wouldn’t hurt to package a few of those similar items together… I say: Stop and think about that. Don’t do it. Package everything separately so there is no cross-transfer.

EVIDENCE TECHNOLOGY: Does your laboratory encourage the submission of swabbings from the crime scene?

MINOR: No, instead of swabbing things, we would prefer—if at all possible—that they submit the entire item. You may get different responses from your readers on that. If it is an immovable object that they obviously cannot submit to us, we will have to deal with the swabbings. Otherwise, we would much rather have the gun submitted, for example, so that we can look for blood in the laboratory and do the swabbing—rather than having ten swabs that someone else took from a gun. With touch DNA really taking hold in this field—that is, testing epithelial cells (skin cells)—we would definitely prefer to have the opportunity to swab items ourselves rather than have someone else do it.


MINOR: Unlike blood, where there usually is an obvious, reddish-brown stain that you can swab, touch DNA is totally invisible. It’s just skin cells. So you have to just learn to approach those cases differently. Working directly with people in our latent-prints section here at the lab, we can collaborate and decide what locations have been handled by the person—and what locations we want to stay away from and save for the latent-print people so that we are not swabbing up a print that you cannot see with the naked eye.

EVIDENCE TECHNOLOGY: How much success have you had with getting good results from touch DNA?

MINOR: It has been pretty successful when collected from things like trigger guards and guns, knives, and tools that have been handled. It is working. If someone transfers epithelial cells on a rough surface and we happen to swab it up, it is going to type.

EVIDENCE TECHNOLOGY: The technology you are using is getting very sensitive, isn’t it?

MINOR: Yes—which brings up another thing that I tell folks about changing their gloves frequently to prevent cross-contamination. It is pretty well understood that when you are at a scene collecting bloody items, you don’t want to touch something, get blood on the gloves, and then handle another item. Everybody knows that. But now we need to start thinking about skin cells. If you are wearing a glove and you handle something that may have been handled by somebody else, you may need to think about changing gloves before you touch the next item. As a matter of fact, if you put on a pair of clean gloves and you inadvertently bring your finger up and scratch your face or nose, then your skin cells are going to be on that glove, and that can go to the next item you touch, as well.

EVIDENCE TECHNOLOGY: How about fingerprint brushes? Can they cause cross-contamination of DNA?

MINOR: Well, that’s a very good question. As a matter of fact, one point in our laboratory’s policy states that items that have been processed for latent prints will not be examined for touch DNA. Most people are not using disposable brushes, from what we understand. The problem with that is going to be if you dust with a brush that has dusted blood samples from a previous case and it gets transferred to an item. If you are lucky enough to get a DNA profile from that item, it could be very problematic because then you have a profile that might not match the suspect because it really came from another crime.

EVIDENCE TECHNOLOGY: A well-publicized report released last year on the DNA Field Experiment stated that when DNA was collected and analyzed from property crimes, twice as many suspects were identified compared to cases where no DNA was collected. Have you seen an increase in samples that are coming from high-volume crime scenes?

MINOR: The answer is definitely Yes. We do those types of cases. And we have always tested high-volume burglary cases. I asked our CODIS administrator, Connie Howard, just what kind of percentage of our high-volume burglary cases lead to hits on other crimes, like rapes and homicides. And it was around 20 percent. That is similar to the numbers reported in the DNA Field Experiment study. So it seems to be consistent with what we are seeing here in Tennessee.

EVIDENCE TECHNOLOGY: I think some readers may reason that if their laboratory is experiencing large DNA backlogs that include samples from rapes and homicides, they may not have the time or resources to deal with samples from less-serious offenses, such as burglaries.

MINOR: Well, maybe a burglary is not the most important case at the time. It is not a homicide or a rape, and we definitely do not want to put that in front of those types of cases. But, on the other hand, analyzing DNA from property crimes has led to solving rape cases and homicides. Definitely, they are worthwhile doing. In fact, that is exactly where your CODIS hits are going to come from.

EVIDENCE TECHNOLOGY: So there should be no inhibitions about sending in samples to the laboratory from high-volume crime cases?

MINOR: There should be no hesitation about sending in samples from high-volume cases. At TBI, we will work these types of cases. I know that you cannot be everywhere, and there are all sorts of cases and robberies out there, and police departments have to prioritize their resources. But if you have that big burglary case that you want tested, just find a way to do it, get the item to us, and we will do the DNA analysis.

EVIDENCE TECHNOLOGY: What about cold cases?

MINOR: We are seeing more and more cold cases come in because we now know that we can develop evidence profiles on these. If a sample has been stored wet or exposed to heat—all the bad things that can happen to DNA—then there is nothing we can do. But when items are just kept stable and dry on a shelf in a property-room, then we can usually get good results. We had one cold case from 1975 where the investigators came to us and said, “See what you can do.” The two analysts who worked on it found some semen stains from this homicide, and they came up with a profile. A suspect was developed, and it matched him, and the case was solved.

EVIDENCE TECHNOLOGY: The technology is really moving things forward, isn’t it?

MINOR: Yes, it is. When STRs started in the late 1990s, we never would have thought that you could go back to a sample from 1975 with success. And we think we may now have some results coming up that go back even further.

EVIDENCE TECHNOLOGY: Thank you for speaking with us today.

A brief look at the background and experience of Joe Minor

Joe Minor is the DNA Technical Manager for the Tennessee Bureau of Investigation (TBI) Forensic Services Division, and Special Agent-Forensic Scientist Supervisor at the TBI Nashville DNA Laboratory. Minor manages DNA grants for the TBI; serves as a member of the Violent Crime Responder Team; instructs forensic science at the Austin Peay State University Department of Chemistry and at the Cumberland University Division of Sciences. He has 25 years of experience in forensic serology and DNA profiling and has testified as a court-qualified expert in over 170 cases. He was selected by the FBI as one of the initial 300 scientists to be trained in RFLP DNA. Minor was also a member of the Department of Education Forensic Science Taskforce, which was responsible for the establishment of the first educational standards in the nation for teaching forensic science in secondary education. Minor received his M.S. in Biology from Austin Peay State University in 1981. He can be reached via e-mail at: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

"A Look at a Laboratory that Cleared its DNA Backlog and Increased Throughput in Just a Few Short Years"
September-October 2009 (Volume 7, Number 5)
Evidence Technology Magazine
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