Current methods in ignitable liquid identification and classification from fire debris rely on pattern recognition of ignitable liquids in total ion chromatograms, extracted ion profiles, and target compound comparisons, as described in American Standards for Testing and Materials E1618-10. The total ion spectra method takes advantage of the reproducibility among sample spectra from the same American Society for Testing and Materials class. It is a method that is independent of the chromatographic conditions that affect retention times of target compounds, thus aiding in the use of computer-based library searching techniques. The total ion spectrum was obtained by summing the ion intensities across all retention times. The total ion spectrum from multiple fire debris samples were combined for target factor analysis. Principal components analysis allowed the dimensions of the data matrix to be reduced prior to target factor analysis, and the number of principal components retained was based on the determination of rank by median absolute deviation. The latent variables were rotated to find new vectors (resultant vectors) that were the best possible match to spectra in a reference library of over 450 ignitable liquid spectra (test factors). The Pearson correlation between target factors and resultant vectors were used to rank the ignitable liquids in the library. Ignitable liquids with the highest correlation represented possible contributions to the sample. Posterior probabilities for the ASTM ignitable liquid classes were calculated based on the probability distribution function of the correlation values. The ASTM ignitable liquid class present in the sample set was identified based on the class with the highest posterior probability value. iv Tests included computer simulations of artificially generated total ion spectra from a combination of ignitable liquid and substrate spectra, as well as large scale burns in 20’x8’x8’ containers complete with furnishings and flooring. Computer simulations were performed for each ASTM ignitable liquid class across a range of parameters. Of the total number of total ion spectra in a data set, the percentage of samples containing an ignitable liquid was varied, as well as the percent of ignitable liquid contribution in a given total ion spectrum. Target factor analysis was them performed on the computer-generated sample set. The correlation values from target factor analysis were used to calculate posterior probabilities for each ASTM ignitable liquid class. Large scale burns were designed to test the detection capabilities of the chemometric approach to ignitable liquid detection under conditions similar to those of a structure fire. Burn conditions were controlled by adjusting the type and volume of ignitable liquid used, the fuel load, ventilation, and the elapsed time of the burn. Samples collected from the large scale burns were analyzed using passive headspace adsorption with activated charcoal strips and carbon disulfide desorption of volatiles for analysis using gas chromatography-mass spectrometry

The research presented in this dissertation describes the design and synthesis of substitutional-solid-solution-based multivariate metal-organic frameworks (SSS-based MTV MOFs) with functionalized organic linkers to study their emergent properties in the crystalline solid state. The synthetic versatility and tunability of organic chemistry coupled with the predictable organization of inorganic structures enables MTV MOF systems to further the fundamental understanding of structure-composition-property relationships for the targeted design of applied materials due to their ability to control the structure, composition, and property independently. To begin, a set of terphenyl linkers with varied steric and electronic properties were crystallized as a family of UiO-type MOFs to assess their effects on the uptake and separation of noble gases. This series was then isoreticularly expanded to PEPEP linkers and combined in a PIZOF-type MTV MOF system to evaluate its capability as a multivariate platform for linkers with different functional groups. Chapters 4, 5, and 6 each focus on a different advantageous aspect of the PIZOF system, first exploring the free volume in the pores where covalently bound redox active mediators demonstrate electron diffusion via charge-hopping mechanics to achieve redox conductivity. The next chapter studies the aggregate-induced emission properties that can arise from link-link interactions due to the interpenetrated structure of PIZOF-type frameworks by incorporating a pentacene-based linker in an MTV MOF series to determine its singlet fission potential. The last chapter utilizes the water stability of the PIZOF framework to investigate how increasing pore hydrophilicity through the inclusion of a rationally designed pentaerythritol-containing linker affects the water adsorption. This dissertation demonstrates the value of the SSS-based MTV MOF approach under the paradigm of reticular chemistry to enable the design of tunable and complex solid-state systems with the ability to deconvolute structure from composition and property, while still allowing for relationships between the structure, composition, and property.

Biological evidence is often found at crime scenes and can comprise of DNA from the victim(s) and perpetrator(s) to a crime as well as from individuals with no direct relationship to the incident. This can complicate analysis as DNA mixtures are one of the more difficult sources of biological evidence to interpret. Probabilistic genotyping (PG) has greatly aided in mixture analysis. However, even with PG, standard bulk mixture approaches do not always result in probative results as allele overlap, artifacts, or low-level minor contributors inevitably cause genotype information loss. Therefore, deconvolution of forensic DNA mixtures into their individual component DNA (geno)types is of great investigative value. In the present work, enhanced single cell DNA typing conditions consisting of reduced reaction volumes and increased PCR cycle number were optimized and paired with a simplified micro-manipulation technique resulting in a subsampling scheme referred to as direct single cell subsampling (DSCS). Furthermore, the PG systems STRmixTM and EuroForMix were validated for use with both standard bulk DNA mixtures as well as with 1-5 cells. The DSCS approach was applied to various complex mixture scenarios including equimolar 2-6 person mixtures, mixtures comprised of 1st degree relatives, mixtures in which a minor donor is virtually undetectable (~1:50), and mixtures that had been deposited for varying time periods resulting in a probative gain of information compared to the standard mixture methods. Specifically, with the 5- and 6- person complex mixtures analyzed, DSCS recovered highly probative LRs ( > 10^20) from donors that had returned non-probative LRs ( < 10^3) by standard methods. With familial mixtures, DSCS prevented the false inclusion of non-donor relatives seen with standard methods. This approach was further applied to Y-STR mixture analysis. The DSCS approach could permit forensic scientists to analyze and recover probative evidentiary information from complex mixtures with excessive overlapping alleles such as those seen with related individuals and large contributor numbers as well as from mixtures with marginally detectable minor donors. Requiring only basic equipment and materials, the DSCS approach can easily be implemented into a casework laboratory.

Analysis of trace evidence involved in sexual assault investigations holds considerable potential as a newer avenue of identification when bulk, larger evidence is not found or unreliable. Trace analysis of forensic materials involves common findings such as strands of hair, residues left on clothing, shards of paint or glass, etc. In recent research focused on the analysis of trace materials found as evidence in a sexual assault, there has been promise in condom and bottled lubricant classification based on their chemical profiles that can provide an associative link in an investigation. Few studies have considered the examination of lubricant evidence at a trace level as it may be found on a crime scene or a victim. In this study, a new protocol will be tested and established to analyze trace lubricant evidence recovered from a fabric substrate, such as underwear, after sexual assaults using Fourier transform infrared (FTIR) spectroscopy. An experiment is proposed to examine the comparison of the spectra resulting from FTIR spectroscopic analysis of bulk and trace level lubricants recovered from a cotton substrate. The resulting spectra will be compared for their similarities using multivariate statistical techniques to test the viability of the approach.

In forensic casework it is often necessary to obtain genetic profiles from crime scene samples that contain increasingly smaller amounts of genetic material, called Low Template DNA (LTDNA). Two examples of LTDNA sources are touch DNA evidence and dust bunnies. Touch DNA refers to DNA that is left behind through casual contact of a donor with an object or another person. Touch DNA can be used to prove a suspect was present at a crime scene. Dust bunnies, or dust conglomerates, typically contain trapped shed skin cells of anyone in the vicinity along with fibers, dirt, hair, and other trace materials. Dust specimens are a potential source of forensic evidence that has been widely underutilized in the forensic community. This is unfortunate because a dust bunny could not only be used to associate a person or crime scene – through trace materials such as fibers – but also to positively identify – through a DNA profile. For example, if a dust specimen is found on a piece of evidence suspected of being moved from its original location, for instance as a body that is too heavy to carry and therefore collects dust while being dragged, then it could be used to link a suspect to a crime scene. Standard methods for obtaining and analyzing touch DNA have been established, but the techniques are not ideal. First, by nature, the 'blind-swabbing' technique, which involves cotton swabs or adhesive tape being applied to an area of interest, can artificially create mixtures of biological material that was originally spatially separated. Second, because the amount of DNA present is typically very low, standard analysis methods may not be sensitive enough to produce probative profiles. In the case of mixtures, the minor component's DNA may go undetected. Dust specimens contain degraded genetic material that has been accumulating for an unknown amount of time. Additionally, dust is usually a conglomeration of genetic material from multiple donors so a mixed profile, if any, is likely to be recovered if standard analysis methods are used. In order to overcome these obstacles presented by LTDNA, a micro-manipulation and combined cell lysis/direct PCR amplification technique has been developed that is sensitive enough to obtain full or probative STR profiles from single or clumped bio-particles collected from touch DNA and dust evidence. Sources of touch DNA evidence such as worn clothing items, touched objects, and skin/skin mixtures are easily sampled using an adhesive material on a microscope slide. Dust specimens can be dispersed onto an adhesive material as well. Targeted bio-particles are then "picked" with a water-soluble adhesive on a tungsten needle and deposited into a micro-volume STR amplification mix. Individual selection and analysis of isolated bio-particles reduces the chance of mixed profile recovery. To aid in the release of genetic material present in the bio-particles, a lysis mix containing a thermostable proteinase is then added to the sample. Samples are then analyzed using standard capillary electrophoresis (CE) methods. In addition to identifying the donor source of these LTDNA sources, it would be beneficial to a criminal investigation to identify the tissue source of the biological material as well. While it is widely speculated that the material originates from shed skin cells, there is little confirmatory evidence proving this assertion. Knowledge of the nature of the evidence could be vital to prevent its misinterpretation during the investigation and prosecution of a crime. Here tissue specific mRNA biomarkers have been evaluated for their use in tissue source determination using a highly sensitive High Resolution Melt (HRM) temperature assay that detects the selectively amplified targets based on their melt temperatures. Using the enhanced genetic analysis technique described above, DNA profile recovery has been markedly enhanced in sources of Touch DNA evidence and dust specimens compared to standard methods. Additionally, the molecular-based characterization method could potentially provide a better understanding of the meaningfulness of the recovered DNA profiles. This optimized strategy provides a method for recovering highly probative data from biological material in low template samples in an efficient and cost effect manner.

The criminal use of explosives has increased in recent years. Political instability and the wide spread access to the internet, filled with "homemade recipes," are two conjectures for the increase. C-4 is a plastic bonded explosive (PBX) comprised of 91% of the high explosive RDX, 1.6% processing oils, 5.3% plasticizer, and 2.1% polyisobutylene (PIB). C-4 is most commonly used for military purposes, but also has found use in commercial industry as well. Current methods for the forensic analysis of C-4 are limited to identification of the explosive; however, recent publications have suggested the plausibility of discrimination between C-4 samples based upon the processing oils and stable isotope ratios. This research focuses on the discrimination of C-4 samples based on ratios of RDX to HMX, a common impurity resulting from RDX synthesis. The relative amounts of HMX are a function of the RDX synthetic route and conditions. RDX was extracted from different C-4 samples and was analyzed by ESI-MS-SIM as the chloride adduct, EI-GC-MS-SIM, and NICI-GC-MS. Ratios (RDX/HMX) were calculated for each method. An analysis of variance (ANOVA) followed by a Tukey HSD allowed for an overall discriminating power to be assessed for each analytical method. The C-4 processing oils were also extracted, and analyzed by direct exposure probe mass spectrometry (DEP-MS) with electron ionization, a technique that requires less than two minutes for analysis. The overall discriminating power of the processing oils was calculated by conducting a series of t tests. Lastly, a set of heterogeneous commercial blasting agents were analyzed by laser induced breakdown spectroscopy (LIBS). The data was analyzed by principal components analysis (PCA), and the possibility of creating a searchable library was explored.

Fire incidents are a major contributor to the number of deaths and property losses within the United States each year. Fire investigations determine the cause of the fire resulting in an assignment of responsibility. Current methods of fire debris analysis are reviewed including the preservation, extraction, detection and characterization of ignitable liquids from fire debris. Leak rates were calculated for the three most common types of fire debris evidence containers. The consequences of leaking containers on the recovery and characterization of ignitable liquids were demonstrated. The interactions of hydrocarbons with activated carbon during the extraction of ignitable liquids from the fire debris were studied. An estimation of available adsorption sites on the activated carbon surface area was calculated based on the number of moles of each hydrocarbon onto the activated carbon. Upon saturation of the surface area, hydrocarbons with weaker interactions with the activated carbon were displaced by more strongly interacting hydrocarbons thus resulting in distortion of the chromatographic profiles used in the interpretation of the GC/MS data. The incorporation of an additional sub-sampling step in the separation of ignitable liquids by passive headspace sampling reduces the concentration of ignitable liquid accessible for adsorption on the activated carbon thus avoiding saturation of the activated carbon. A statistical method of covariance mapping with a coincident measurement to compare GC/MS data sets of two ignitable liquids was able to distinguish ignitable liquids of different classes, sub-classes and states of evaporation. In addition, the method was able to distinguish 10 gasoline samples as having originated from different sources with a known statistical certainty. In a blind test, an unknown gasoline sample was correctly identified from the set of 10 gasoline samples without making a Type II error.

The fire debris analyst is often faced with the complex problem of identifying ignitable liquid residues in the presence of products produced from pyrolysis and incomplete combustion of common building and furnishing materials. The purpose of this research is to investigate a modified destructive distillation methodology provided by the Florida Bureau of Forensic Fire and Explosive Analysis to produce interfering product chromatographic patterns similar to those observed in fire debris case work. The volatile products generated during heating of substrate materials are extracted from the fire debris by passive headspace adsorption and subsequently analyzed by GC-MS. Low density polyethylene (LDPE) is utilized to optimize the modified destructive distillation method to produce the interfering products commonly seen in fire debris. The substrates examined in this research include flooring and construction materials along with a variety of materials commonly analyzed by fire debris analysts. These substrates are also burned in the presence of a variety of ignitable liquids. Comparisons of ignitable liquids, pyrolysis products, and products from pyrolysis in the presence of an ignitable liquid are performed by comparing the summed ion spectra from the GC-MS data. Pearson correlation was used to determine if substrates could be discriminated from one another. A pyrolysis products database and GC-MS database software based on comparison of summed ion spectra are shown to be useful tools for the evaluation of fire debris.

Discovering, screening, and associating changes in DNA sequence are important to a broad range of disciplines and play a central role in Forensic Science. The typical types of changes include sequence variations [single nucleotide polymorphisms (SNP)] and length variations [short tandem repeats (STR)]. The steps for forensic DNA sample processing are similar for both types of changes but diverge at the point of detection. A number of approaches are being explored for SNP genotyping while STR analysis primarily consists of size-based analysis by capillary electrophoresis. Limitations exist for all current detection methods that pose significant impacts to forensic analysis. Bi-allelic SNPs result in three possible genotypes with a minimal amount of information generated per marker. Limitations for SNP analysis are due to the inability to amplify a suitable number of SNP markers from low DNA content samples to provide an appropriate level of discrimination. Multi-allelic STR markers are currently the marker of choice for forensic typing but a variety of experimental artifacts are possible that consist of either biology or technology related causes. Molecular genotyping methods developed across other disciplines have potential to alleviate some of these shortcomings but no current approach is capable of genotyping both SNP and STR loci with a single chemistry. The need for a more effective, efficient, and generalized approach led to development of a unique method called Dye Probe Fluorescence Resonance Energy Transfer (dpFRET) and determination of its suitability for forensic analysis. The development phase of the research consisted of synthetic testing to establish proof of concept for the chemistry followed by polymerase chain reaction (PCR) based assays to demonstrate real world applications. Following successful development, the boundaries and limitations for the technology were established (sensitivity, allelic dropout, mixed samples) and efforts were made to improve the approach. In the process, parallel testing for other fields including molecular pathology and conservation biology were incorporated to explore potential widespread application of this new approach. The overall goal of this project was to develop and explore the limitations for a unique approach to genotyping both SNPs and STRs. A majority of the work involved development of the method itself with the ultimate objective of application for forensic science. The focus of this project was to address and alleviate some of the shortcomings of current approaches that result in potential limitations for forensic analysis. It is expected that future applications of this technology might impact a wide range of disciplines to aid in discovery, screening and association of changes in DNA sequence.

Triacetone Triperoxide (TATP) is a primary high explosive that can be synthesized using commercially available starting materials and has grown in use among terrorists over the past several years. Additives present in the precursors were investigated to see if they carry through the TATP synthesis and can be detected in the final product potentially aiding in the identification of the source. Additives identified in the acetones were also identified in pre-blast and in some post-blast samples. However, these additives are present in trace quantities relative to the TATP, which coupled with the volatility and short lifetimes of some of the additives in TATP samples limit their detection in pre-blast and post-blast material. TATP prepared with different acids in the laboratory could generally be discriminated by observing the change in composition of the headspace of the samples upon heating and by IMS analysis of the crystals. The analysis of TATP synthesized on a larger scale was compared to the laboratory results of pre-blast material and post-blast debris. As in the laboratory samples, organic additives were also detected in the large-scale pre-blast samples and the identification of the additives in post-blast debris was consistent with the results obtained in the laboratory detonations.