Samantha Strong posted        There are a few different ways to detect accelerants and explosive material

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Samantha Strong posted

 

     There are a few different ways to detect accelerants and explosive material. One way is by the use of a mass spectrometer. A Mass spectrometer (MS) can be used to detect such things as chemical warfare agents, pesticides, explosives, drugs, and possible accelerants (Gupta and Samal, 2022). IRTD-DART-MS-infrared-thermal-desorption Direct analysis in real-time mass spectrometry (IRTD-DART-MS) allows the investigator to test for explosives by using a wipe on a surface such as metal, glass, wood, tape, polymers to name a few (Gupta and Samal, 2022). For Accelerant analysis, it can be used to determine how the fire was set. Besides a DART-MS an investigator could also use a gas chromatography MS or a Solid phase micro-extraction MS (Gupta and Samal, 2022). The investigator would take any evidence from the crime scene like debris, liquids, and flammable solvents and run tests on them in the different types of mass spectrometers to see if any accelerants can be detected (Gupta and Samal, 2022). Investigators also use a dog’s sense of smell to detect any explosives or accelerants as well as drugs. dogs have more olfactory receptor cells which are neurons that extend out into the airspace and interact with other odorants creating a unique smell (Kokoci?ska-Kusiak et al., 2021). Dogs also have a larger olfactory bulb which is created from bundles of nerve fibers (Kokoci?ska-Kusiak et al., 2021). The larger olfactory bulb processes and filters olfactory information, which allows dogs to distinguish between odors, and enhance the sensitivity of odor detection while simultaneously filtering out background odors, which then allows them to find and hone in on certain odors (Kokoci?ska-Kusiak et al., 2021). Dogs generally are sensitive to odor and can recognize more smells than it has receptors for scent molecules, and eventually, they can be trained to smell unique patterns connected to different odors (Kokoci?ska-Kusiak et al., 2021). The use of dogs, as well as lab tests, can improve the efficiency of detection of searched substances, and could eventually lead to the even offer identification of particular compounds (Kokoci?ska-Kusiak et al., 2021).

     Anna Palmer was a 10-year-old girl who was found on her front porch stabbed several times in the throat and was sexually assaulted on September 10, 1998. It was reported by Anna’s friend Loxane Konesavanh that a man was following them as they walked to their mutual corner before parting to go to their separate homes (Mendoza, 2022). This story was corroborated by another girl named Amie Johnson who said that she saw a man follow Anna down her block. Other than the eyewitness testimony there was little to go on and the case eventually went cold (Mendoza, 2022).  In 2009 with the advancements in DNA technology the evidence from Anna’s case was reexamined. Investigators reexamined body swabs, clothes, and other pieces of evidence collected from the scene. Investigators took DNA from under ANna’s fingernails and sent them to the lab (Mendoza, 2022). Utilizing alternative light sources to get the DNA from under the fingernails, the sample was significant enough to create a profile (Mendoza, 2022). That profile was matched to a man named Matthew John Beck, who was 19 years old at the time of Anna's death. It was found that Matthew lived close to Anna’s home in 1998. When his DNA was discovered on Anna he was found to have already been serving time in a prison in Idaho for sodomizing a minor. Matthew was charged and pleaded guilty in 2011 to murdering Anna (Mendoza, 2022). He was sentenced to life in prison without the possibility of parole (Mendoza, 2022).

     CODIS is the Combined DNA Index System that is used to describe the FBI’s program of a DNA database that was started in 1994 (Federal Bureau of Investigation, n.d.). CODIS was initially established by Congress to aid law enforcement in obtaining leads for cases where a suspect has yet to be identified.  This system contains DNA profiles contributed by federal, state, and local participating forensic laboratories where they can be accessed to match samples to possible suspects (Federal Bureau of Investigation, n.d.). The system allows law enforcement to obtain a match for the suspect or it can link more than one crime scene together which makes it easier to make the connection of a serial offender (Federal Bureau of Investigation, n.d.).  

 

 

 

Nickitias Johnson posted

Describe the tool utilized at a crime scene to detect accelerants and explosive material.

The tool used at a crime scene to detect accelerants and explosive materials is Ion Mobility Spectromery (IMS) -based trace explosive detectors for first responders report. This tool premise is to trace detection that anyone who handle explosives will leave microscopic, invisible traces on anything they have touched (DHS). They can find fingerprints on personnel items such as clothing, hair, steering wheels, laptop computers etc. These fingerprint residues contain enough explosives to be detected by this instrument.  Places that IMS are normally used are by the airports, by the U.S. Military to screen, mail, people, and vehicles and by the coast guard to screen ships and cargo. 

 

Another tool used at a crime scene to detect accelerants and explosive materials is infrared hyperspectral imaging. This tool is used to provide a fast, non-contact, noninvasive and non-destructive method for the analysis of explosive residues on human handprints (Ossa)

Discuss a real case in which DNA analysis was utilized to identify the offender. Be sure to include a discussion about the biological evidence collected at the crime scene and the type of DNA analysis utilized.

 

The case I chose was when DNA was in its infancy stage. In 1986 a woman in Florida was raped by a man who had broken into the home and held her at knifepoint. In that same year 22 other woman was sexually assaulted in the same manner. In all of these attacks the suspect broken in through an unlocked door or a window and each time he was careful not to eave fingerprints.  In addition, his face was always concealed except at the first crime scene (Sundquist).  Which they knew that would not be enough to convict him.

 

Jeffery Ashton the assistant attorney for the state saw an ad that advertised DNA based paternity testing. He did wonder if that would help him catch his guy. At this time, it was very difficult to identify the suspect on serology alone, there needed to be more evidence. At another crime scene two fingerprints were left on a window screen which gave hope but there was no match in the database for these prints (Sundquist).

 

The break came in the case when the suspect was called in by a woman whose apartment he was trying to break into. They were able to arrest him and identify him as Tommie Lee Andrews who fingerprints, and semen matched the crime scene.  Along with a positive identification from the first victim before he started concealing his face. 

 

Going back to the seaman and the ad the assistant state attorney asked the state attorney if they could use the paternity test for testing the seaman in this criminal investigation case. He said yes and the contacted Lifecode Corp a lab in NY that was conducting paternity test. Life crop told them that the test is applicable to anything that would have DNA in it, and they perform the test.  The tests results were that there was only 1 in 10 billion chances that Andrew DNA and the DNA found at the crime scene was a random match.  An expert whiteness testified, and Andrew was convicted for 22 years and making him the first person to be convicted as a result of DNA (Sundquist). 

 

Discuss the development of the CODIS database.

 

The Combined DNA Index System began a pilot program in 1980.  Its job was to blend forensic science with computer technology in order to be able to link violent crimes. Its mission is to provide and support federal, state, and local crime labs I the United States the comparisons and exchange of forensic DNA evidence from violent crimes. Their teams consisted of paralegals, biologists, auditors, forensics systems program managers and program analysts. Within CODIS is an integral part called NDIS which is the National DNA Index System. 

 

Today this program has 153 participating laboratories which represents District of Columbia and 49 other states. In March 2002 this system assisted in over 4, 719 investigations in 32 states and 2 federal laboratories (Adams). What’s stored in the in the database is a DNA profile also known as a DNA Type. This DNA profile consists of one or two alleles at the 20 CODIS Core Loci. It’s important to know that no names or personal identifies are stored in this database.  What you will find is the DNA Profile, the specimen identification number, the agency identifier, and the DNA laboratory associated with the DNA profile analysis.