Larry -Watson Week 3 Writing Assignment Preliminary Field and Laboratory Testing 17 FEB 2020

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Running Head: Field and Laboratory Testing 1 Crime Field and Laboratory Testing Larry Watson CRJ 311 Forensics Professor Ginger Devine Date February 17, 2020

2 Field and Laboratory Testing Identifies What Types of Evidence Might Be Subjected to Preliminary or Field Testing? First and foremost, the evidence must be applicable to the investigation and it should be part of the field testing to assist with identifying the evidence at the crime scene. With that being said, there are an array of evidence that is not admissible in the court, this could play a major role for an investigator who is trying to link the evidence to his/her case. Also, there is evidence that is not admissible by itself that could be admissible with a combination of other types of evidence. One type of evidence that would be subject to field testing at the crime scene is when an individual has been stopped by a police officer, and during a routine traffic stop the officer smells a strong odor of marijuana, then during their vehicle search they find drugs and drug perphilenaila' in plain sight in the vehicle that can be subjected to field testing. “Fingerprint reagents and development techniques are generally intended to be used in combination and sequential order, these methods are often specific to either porous or nonporous substrates; however, some techniques have universal applications” (Weaver, D. E.1993). They are for the police officers who now have probable cause to conduct a preliminary field test of the drugs to verify if it’s negative or positive. And secondly fingerprinting evidence. There are several items that prints could not be lifted from in the past, such as burned items, which can now be analyzed. There are numerous prints that a crime scene investigator could find at a crime scene. Fingerprints can also be found on surfaces, such as paper, unfinished wood and cardboard, all of which can hold prints and can be field tested on the crime scene by a Latent print expert. You also can conduct preliminary testing on blood found at the crime scene, test it to verify if it’s human blood or not.

3 Field and Laboratory Testing Two Types of Testing That Might Be Done On-Scene? There are numerous types of testing that is done at the crime scene to assist the crime scene investigator. Collecting trace evidence, which may include gun-shot residue (GSR), to include illicit drugs, chemicals and glass found at the crime scene. Certain types of evidence require different methods of collection and field testing. In situations where the crime involved has a gun, when collecting evidence, the crime scene investigator will collect all clothing from anyone involved and anyone who may have been at the scene there clothing will be tested at the lab for gun-shot residue (GSR). “According to (Gaensslen & Larsen 2019) that gunshot residue cannot prove that someone fired a weapon; it only shows that the person's hand was in the vicinity of a fired weapon” (Gaensslen, R. E., & Larsen, A. K. (2019). This can help eliminate anyone not involved, by testing their hands and clothing for any gunshot residue. Another type of preliminary field testing that can be conducted at the crime scene is footprints and tire tracks. Shoeprints are frequently recovered at crime scenes, more than likely these impressions can be compared to the suspect’s shoes and tire tracks to verify that a particular type of shoes/tire tracks impressions was left at the crime scene. “Shoeprint evidence collected from crime scenes can play an important role in forensic investigations” (lmaadeed, S., Bouridane, A., Crookes, D., & Nibouche, O. (2015). Shoes and the tire tracks impressions will be photographed from direct angles over the impression capturing the size and if possible, the type and certain styles of the tire and shoe impressions. Further testing at the crime laboratory will help with the credibility of the evidence in the court proceeding.

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4 Field and Laboratory Testing Differentiates Between Why Some Evidence Can and Should Be Subjected to Preliminary Testing on Scene While Other Types Should Not? Evidence such as blood stains, weapons, fingerprints, and tire tracks located at the crime scene should not be tested at the crime scene because these types of evidence requires a forensic scientist to conduct their analysis of the evidence in order for the evidence to be admissible in court. “The manufacturer, Thermo Fisher Scientific, sells a kit that makes heroin testing possible” ( Kucher, K. (2018, October 7). Time sensitive evidence such as drugs and blood stains found at the crime scene should be subjected to preliminary testing at the crime scene, this could possibly help the prosecutor or prevent the defendants from being charged with a crime, and with that being said, preliminary field testing on the scene should be allowed. Explains How the On-Scene Test Compares to Laboratory Testing. It is extremely important that all laboratory testing is tested in a secure environment to prevent any of the evidence from becoming contaminated. The testing laboratory scientist will perform their testing to provide their analysis under a regulated environment that will be certified by a forensic scientist. This is a must because some of the evidence must be stored at certain temperatures to preserve the evidence for future use, such as DNA evidence. Let’s move on to the On-Scene Test of the evidence. This is collected in a more rapid fashion due to the sensitivity of the evidence. “While on-scene tests determine the general characteristics of a material thus helping the investigators to narrow down the field to be confirmed” (Gaensslen and Larsen 2019). On scene testing evidence that is found at the crime scene can become contaminated due to other people walking through the crime scene because the crime scene during the initial phase is not controlled or secured until a uniform police officer secures the crime scene.

5 Field and Laboratory Testing Compares and Contrasts the Results Yielded by Preliminary Field Versus Laboratory Testing. The preliminary field testing of the evidence is collected in a field environmental setting. The crime scene investigator is responsible for getting evidence, analyzing, transcribing, and photographing the evidence in real time, that can be critical because the investigator must capture every piece of evidence at the crime scene. Laboratory Testing forensic scientists have a major impact on our criminal justice system, because forensic science can either prove someone innocent or guilty of a crime. Compares and Contrasts the Admissibility of On-Scene Versus Laboratory Testing at Trial. Evidence found on the crime scene can be admissible, if all of the evidence at the crime was collected, documented, photographed, and submitted into evidence, it will be considered to be evidence that is admissible in court. “Witness’s testimony is the main way of authenticating evidence because witnesses can identify an object in court, for example, a witness can authenticate a document that is familiar by recognizing either the document or the signatures” (Gaensslen and Larsen 2019). Laboratory testing evidence that is introduced as evidence through the findings by a forensic expert can be used as admissible evidence. For example, evidence submitted to a forensic scientist to link to a specific individual for a rape case, through a positive semen test / DNA results will be admissible in court.

6 Field and Laboratory Testing Conclusion In conclusion it is very important that both preliminary field and laboratory testing research plays a major part in the criminal justice system. The Evidence that is collected and documented properly at the crime scene can be admissible in court. I also discussed the type of evidence that is subject to field testing and how field testing compares to laboratory testing and what is admissible in court.

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7 Field and Laboratory Testing Reference Cassidy, B. M., Lu, Z., Martin, J. P., Tazik, S. K., Kellogg, K. W., DeJong, S. A., Belliveau, E. Gaensslen, R. E., & Larsen, K. (2019). Introductory forensic science (2nd ed.). Retrieved from http://content.ashford.edu/ lmaadeed, S., Bouridane, A., Crookes, D., & Nibouche, O. (2015). Partial shoeprint retrieval using multiple point-of-interest detectors and SIFT descriptors . Integrated Computer-Aided Engineering, 22(1), 41–58. https://doi.org/10.3233/ICA-140480 Forensic Science International, 285, 147–160. https://doi.org/10.1016/j.forsciint.2018.02.002 https://dps.mn.gov/divisions/bca/bca-divisions/forensic-science/Pages/trace-shoeprints- tiretracks.aspx

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