Research by Miami-Dade PD, via the NIJ.
Register now to reserve your spot at this years conference. I’ll be there, doing workshops on fingerprints, basic photography and/or forensic light sources. The last two conferences have been great, and this is a wonderful opportunity to come out, learn some new things and interact with other CSIs from across the US and around the world. (Past attendees have arrived from Poland, Taiwan, Jamaica, Belize, a number of Caribbean islands, Australia and Pakistan).
This is an excellent training event, and the fellowship with investigators from around the globe is a great thing to see.
Daryl W. Clemens
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
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.
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
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): https://www.ncjrs.gov/pdffiles1/nij/grants/248682.pdf
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.
The 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!
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
December 1-3, 2014
Location: HCSO Training Facility
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.