Author Archives: dclemens

About dclemens

Daryl Clemens has been a crime scene investigator for 20 years, and also teaches classes in crime scene investigation, forensic science and photography.

Tools for Improving the Quality of Aged, Degraded, Damaged, or Otherwise Compromised DNA Evidence

By Michael M. Cox, Ph.D., Evelyn M. Mercer
Published by the NIJ

Almost every day, DNA samples are collected from the scenes of crimes or disasters that are too degraded for standard forensic DNA analytical procedures. This fact represents an ongoing impediment to law enforcement and victim identification efforts. Many law enforcement agencies also possess archived crime scene evidence from cold cases that are decades old, in which the DNA has become too damaged to analyze. The major problem in these samples is the presence of DNA double strand breaks. The purpose of the work carried out under grant 2010-DN-BX-K190 is to develop a new method to repair double strand breaks in forensic DNA samples, as a pretreatment for the standard STR analysis protocols. As part of this effort, we have also developed reproducible procedures for the artificial degradation of human DNA samples, using ionizing radiation to inflict a DNA damage profile that reprises that of a typical degraded forensic sample. Using this type of DNA as a test bed, we have developed a protocol that is successful in increasing/restoring missing or substandard signals at two STR loci. The protocol utilizes the bacterial RecA protein, single-stranded DNA binding protein (SSB), and bacterial DNA polymerase I, in concert with a targeting oligonucleotide. The reactions promoted by these reagents effectively restore damaged DNA flanking a particular STR locus. With the most developed protocol, signal restoration is successful approximately 20% of the time. With a few exceptions, the restored signals are accurate. The artifacts arising in the exceptions have been traced to the targeting oligonucleotides. Efforts to further develop this technology are continuing, focused on new RecA protein variants that increase signal strength and re-designed targeting oligonucleotides.

We have also been successful in demonstrating proof of principle in efforts to recover targeted DNA segments and remove them from bulk DNA in an effort to concentrate them and eliminate conditions that could inhibit STR amplification.

Read the full paper Here

Bugs: the difference between closed case and unsolved murder


MSU partners with Detroit to investigate death scenes

EAST LANSING, Mich. – As bodies decompose, their types and numbers of bugs and bacteria change. Deciphering the clues they provide could mean the difference between a closed case and an unsolved murder.

Michigan State University is using a more than $866,000 U.S. Department of Justice grant to help Detroit death-scene investigators examine these changing populations. The microbial communities may provide crucial details such as geographical location of death, gender, race, socioeconomic relations and more, said Eric Benbow, MSU entomologist and osteopathic medical specialist.
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Bloodstain Patterns on Textile Surfaces: A Fundamental Analysis

Bloodstains on fabric

Bloodstains on fabric

Article authored by: Stephen Michielsen, Michael Taylor, Namrata Parekh, Feng Ji


Bloodstain pattern analysis, BPA, on hard surfaces (such as walls, tables, appliances, hardwood floors, etc.) has grown into a science-based investigative tool that can help determine scenarios that are consistent with or counter to the events described by witnesses or suspects. At the vast majority of crime scenes involving a bloodletting event, textiles are present as apparel, household textiles (sheets, towels), upholstery, carpets, and so forth. Yet, the science of BPA is not able to render the same level of confidence in the analysis as on hard surfaces due to the complex structure of textiles and their ability to wick liquids. In the work described herein, a detailed examination of factors that affect BPA on two textile fabrics, an unbalanced 130 x 70 plain woven 100% cotton bed sheeting fabric (often referred to as a 200 thread count bed sheet) and a 100% cotton jersey knit T-shirt fabric.

During this study, both porcine blood and several synthetic blood recipes were used. The dynamic impact tests (time after impact < 100 ms) used porcine blood, while most wetting and wicking experiments employed synthetic blood (time after impact > 100 ms). Most of the synthetic blood recipes examined performed badly. Either they would not dry or they did not wick into the fabrics, but remained on the surface. A synthetic blood recipe from the American Society for Testing Material (ASTM test method F1819-07) performed well, but its viscosity and surface tension were both lower than typical human blood. Thus, this recipe was modified to lie within the range of surface tension and viscosity of human blood. It was used for the majority of wicking and wetting experiments. In a preliminary comparison, it was found that synthetic blood SB5 behaved similarly to porcine blood in many aspects, but the SB5 stains were significantly larger than the porcine bloodstains. We attributed this difference to the presence of red blood cells, which behave as particles, as well as plasma, which behaves as a liquid, in porcine blood. SB5 is an aqueous solution and behaves entirely as a liquid. Continue reading

New Study on Survivability of DNA Evidence

A new study published by the NIJ, demonstrates positive recovery of DNA for up to 10 days following intercourse. Given various circumstances that may lead to delays in reporting or testing, it’s good to know that current testing methods may still yield results even with a substantial delay.

The study can be accessed here (in .pdf format):

Crime Scene Investigation and Fingerprinting

Interesting historic video on crime scene investigation and forensic science. I have a copy as well, that I purchased on DVD from the National Archives. The date on the original is a bit unclear, but it appears to have been made around 1960. It should be noted that some of the practices shown are no longer up to date, and that current safety precautions are not in use. It’s still interesting from a historical standpoint.

Crime Scene Investigation Conference

imagesThe International Crime Scene Investigators Association will be holding their second annual conference in New Orleans, May 19-21, 2015. So far there are attendees registered from 14 countries. Last years conference was great, and this years promises to be better still. I expect to be there, and I hope to see some of you as well!

Where There’s Smoke Arson Investigation Program

Walk through two complex arson cases at top LASD investigator Ed Nordskog’s latest forensic science seminar

WHAT: Cal State Los Angeles Professor Donald Johnson, in association with LAVA – The Los Angeles Visionaries Association and Esotouric, present a new program in their quarterly forensic science seminar series: “Where There’s Smoke” hosted by Ed Nordskog, top arson investigator for the Los Angeles Sheriff’s Department. Continue reading

Advanced Topics in Homicide

December 1-3, 2014
Location: HCSO Training Facility
Time: 9:00am-5:30pm

USF-HCSO is co-hosting a 3-day workshop (24 hour training) for detectives, crime scene personnel, death investigators, prosecutors and defense attorneys, as well as other forensic specialists who work in the area of violent crime investigations.

This course will focus on the following themes: long-term unsolved cold cases; clandestine grave search and recovery; child victims from abduction to homicide; and sexual homicide. The Dozier Reform School investigation will be discussed in-depth, as a case study for field methods used for grave search and recovery.

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MAFS Forensic Anthropology Workshop

MAFS is announcing a Forensic Anthropology Workshop hosted by the Johnson County Sheriff’s Office Criminalistics Laboratory in Olathe, Kansas on June 17th – June 19th.

This is a 3-day course instructed by a world-renowned expert in the area of FORENSIC ANTHROPOLOGY, Dr. Michael Finnegan, Board Certified Forensic Anthropologist and Kansas State University Professor of Physical Anthropology (retired). This class is designed as an introduction to Forensic Anthropology and is geared towards Crime Scene Responders, Medical Examiners, Coroners, Death Investigators, Detectives, Forensic Nurses, Attorneys, and Students seeking a greater understanding of the forensic use of BONES and the contexts by which human remains are found in natural and unnatural settings.

Participating students will be presented information on proper scene documentation (photography and mapping); the use of GPS and GIS for scene scouting/planning and reconstruction of the recovery site; procedural steps in the documentation and recovery of human remains from surface scattered to clandestine burial conditions; the impact of anthropology on criminal investigations; laboratory methods for the identification of human remains; human remains in mass fatality events, and case examples by the instructor. HANDS-ON ACTIVITIES will occupy half of the class, including a “BIG DIG.”

For more information and to register for this workshop, go to

CSI Training

The International Crime Scene Investigators Association will he holding a training conference in Little Rock, AR. May 13-15, 2014.  This is truly an international conference with presenters and attendees from across the US, Caribbean and the UK to name a few.

There is still space available, so don’t miss out on this great opportunity.

You can find out more on the conference website: