Time filter

Source Type

Quantico Station, VA, United States

Christensen A.M.,Federal Bureau of Investigation Laboratory | Leslie W.D.,University of Manitoba | Baim S.,University of Miami
Forensic Science International | Year: 2014

In forensic anthropological contexts, very few methods of estimating ancestry from the postcranial skeleton are available. The cranium is widely recognized to show the greatest ancestral variation, and is often regarded by forensic anthropologists as the only reliable bone for estimating ancestry from unidentified skeletal remains. Several studies have demonstrated ancestral variation in aspects of the femur, but none have shown significant predictive power for discriminating multiple groups, and have therefore not gained wide acceptance by forensic anthropologists. Skeletal health experts (particularly bone densitometrists), however, have long recognized a relationship between proximal femur geometry (especially hip axis length) and osteoporosis-related fracture risk. Moreover, fracture risk has been noted to vary between ancestral groups. Here, we investigate whether measurements that are related to fracture risk might also be used to estimate ancestry from unidentified skeletal remains. Specifically, we investigate ancestral differences in femoral neck axis length (FNAL) and find significant differences between European, Asian and African groups in both women and men. FNAL was largest in European groups followed by African and then Asian groups. The greatest discriminating power was found between European and Asian groups, but was also significant between European and African groups. These differences may have utility in estimating ancestry in forensic anthropological contexts. © 2014 Elsevier Ireland Ltd.

Bottegal M.,Treasury Obligations Section | Lang L.,Forensic Science Laboratory Washington | Miller M.,Federal Bureau of Investigation Laboratory | McCord B.,Florida International University
Rapid Communications in Mass Spectrometry | Year: 2010

Black powder substitutes are an important sub-group of explosive propellants in the United States because they are readily accessible, and can be used as fillers for improvised explosive devices. Many brands of black powder substitutes incorporate an ascorbic acid fuel source with potassium nitrate (KNO3) and/or potassium perchlorate (KClO4) oxidizer(s). A gradient high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-QToFMS) method has been developed for the analysis of both the organic and the inorganic constituents. The HPLC/ESI-QToFMS method was utilized to examine aqueous extracts of intact samples and post-burn residues from six different brands of ascorbic acid based powders. Aqueous extracts of the post-blast residues from two brands of ascorbic acid based propellant were also analyzed. The results showed that both the ascorbic acid fuel and the inorganic oxidizer(s) KClO4 and/or KNO3 were successfully detected via the [M-H]- ion of ascorbic acid and the anions (ClO- 4and NO- 3-) of the oxidizers. This method was proven to be a rapid and efficient procedure for the analysis of this class of explosives. The high mass resolution provided by the QToFMS instrument fulfills the degree of certainty required in a court of law.

Sarment D.P.,Private Practice | Christensen A.M.,Federal Bureau of Investigation Laboratory
Journal of Forensic Radiology and Imaging | Year: 2014

Cone beam computed tomography (CBCT) is a relatively recently-developed CT technology that is currently used primarily in maxillofacial applications. CBCT may also be very useful in some forensic contexts, offering several advantages for postmortem forensic imaging including good resolution for skeletal imaging, relatively low cost, portability, and simplicity. Here we present an overview of CBCT technology, comparing and contrasting to conventional CT in regards to various forensic applications, and conclude that CBCT may be an advantageous and accessible alternative in many cases. © 2014.

Tarvin M.,Federal Bureau of Investigation Laboratory | McCord B.,Florida International University | Mount K.,Federal Bureau of Investigation Laboratory | Sherlach K.,Federal Bureau of Investigation Laboratory | And 2 more authors.
Journal of Chromatography A | Year: 2010

Two complementary methods were optimized for the separation and detection of trace levels of hydrogen peroxide. The first method utilized reversed-phase high-performance liquid chromatography with fluorescence detection (HPLC-FD). With this approach, hydrogen peroxide was detected based upon its participation in the hemin-catalyzed oxidation of p-hydroxyphenylacetic acid to yield the fluorescent dimer. The second method utilized high performance liquid chromatography with electrochemical detection (HPLC-ED). With this approach, hydrogen peroxide was detected based upon its oxidation at a gold working electrode at an applied potential of 400mV vs. hydrogen reference electrode (Pd/H2). Both methods were linear across the range of 15-300μM, and the electrochemical method was linear across a wider range of 7.4-15,000μM. The limit of detection for hydrogen peroxide was 6μM by HPLC/FD, and 0.6μM by HPLC/ED. A series of organic peroxides and inorganic ions were evaluated for their potential to interfere with the detection of hydrogen peroxide. Studies investigating the recovery of hydrogen peroxide with three different extraction protocols were also performed. Post-blast debris from the detonation of a mixture of concentrated hydrogen peroxide with nitromethane was analyzed on both systems. Hydrogen peroxide residues were successfully detected on this post-blast debris. © 2010.

Jagerdeo E.,Federal Bureau of Investigation Laboratory | Montgomery M.A.,Federal Bureau of Investigation Laboratory | Karas R.P.,Federal Bureau of Investigation Laboratory | Sibum M.,Spark Holland Inc.
Analytical and Bioanalytical Chemistry | Year: 2010

Marijuana is one of the most commonly used illicit substances. The high usage of this substance results in it being commonly encountered in clinical samples throughout the USA and Europe. Due to its wide availability and use, marijuana is also commonly encountered in forensic toxicology laboratories. The proposed method utilized an automated solid phase extraction (SPE) coupled to liquid chromatography/mass spectrometry (LC/MS). The automated SPE procedure was developed using Hysphere C8-EC sorbent, and the high performance liquid chromatography (HPLC) separation was performed using an Xterra MS C18 column with a total runtime of 10 min. The standard curves linearity generally fell between 6 and 500 ng/mL. The limits of detection ranged from 2 to 4 ng/mL, and the limits of quantitation ranged from 8 to 12 ng/mL. The bias and imprecision were determined using a simple analysis of variance (single factor). The results demonstrate bias as <11% and percent imprecision as <12% for all components at four quality control levels. This method has been in use for over 2 years and has been applied to numerous forensic samples. When compared to other published methods, it exceeds others in its simplicity and speed of analysis. This method takes advantage of robotics and automation for a total analysis time of 10 min, including sample preparation, separation, and detection. © 2010 US Government.

Discover hidden collaborations