The use of DNA and modern technology in crime investigations

Forensic Investigations 

The criminal justice system of all governments is responsible for investigating crimes. However, technological advancement and the continued development of criminals in perpetrating crimes means that criminals are always steps ahead of the legal agencies. Investigative officers and agencies have enhanced the use of science and technology in the bid to prosecute criminals for advanced criminal activities. Traditional investigations inadequacy in convicting suspects in crimes that had no witnesses led to the use of DNA evidence to confirm whether the suspect was innocent or guilty. The use of DNA evidence paved way for forensic investigations and use of technology in cybercrimes and use storage devices to solve cases. Therefore, the purpose of this essay is to define, describe and analyze the use of DNA and modern technology in crime investigations. The essay has four sections divided with question one and two addressing the use of DNA collection, evidence handling and cases that used DNA to exonerate and convict criminals. Question three addresses the use of computers and mobile phones during investigations. Lastly, question four investigates arson and explosive investigations.

Question 1 

Blood is the most common fluid encountered in crime scenes. The blood components such as blood cells, hemoglobin, hormones, and other plasma are essential in DNA investigations because these components make it difficult to clean blood stains. Therefore, investigators undertake presumptive tests to establish whether the stain in the crime scene is in fact blood. The investigators are likely to use a chemical termed as luminol which confirms the existence of blood by having a blue luminescence color (Baker, 2010). Luminor reagent color change is due to the oxidation by the iron in the hemoglobin. However, reactions with ion, copper, cobalt ions, potassium, and iron compounds may lead to false positives or false negatives. In most cases, the luminol is used for presumptive tests in clothes with the stain expected to be dried before being added to the chemical.

Due to the reactions, other alternative chemicals used are phenolphthalein used in Kastle-Meyer reagent which is mixed with 95% ethanol and passed through a filter paper containing the suspected bloodstain cause a red or pink solution (Catalin, Andrei, & Mitrasca, 2015). However, the determination of blood presence is only noted after the addition of hydrogen peroxide and the existence of a pink solution. The collection of bloodstains should be performed without contaminating the crime scene thus use of clean cotton cloth where the blood is liquid and drying it for at least an hour before undertaking the tests. If the bloodstain is on clothes the cloth is dried via a fan and lapped in a paper or in an envelope. If the stain is on the floor or an immovable surface scrubbing the stain with a clean object and storing it in an envelope is the best way to collect the specimen. Suspected bloodstains on knives and other objects are scrubbed and stored as earlier stated with the samples and the knife stored separately. The collecting officer should label all the evidence after collecting. The labeling includes the case, location of the crime, the area the evidence was collected, the evidence and the collecting officer’s name. The information is important in documentation in forms that make it easier to refer to during analysis processes. Lastly, it is important for the collecting officer to ensure that evidence from one place does not contaminate another crime scene. For instance, the officer should wear gloves when collecting evidence for the bedroom remove them and wear other gloves to collect evidence from the kitchen or any other part.

Blood patterns in crime scenes are vital for the investigators to recreate the incident that happened before and after the crime. The scientific fact that blood spatters patterns, transfer, marks and other voids fulfills the claim made earlier. Bloodstain pattern experts use the blood pattern based on the behavior of blood, cohesion, capillary action, and velocity, distance, angle, and geometry to answer multiple questions regarding the bloodstains. The pattern shows the source of the blood, wounds or the object used, the direction of the victim and perpetrator, movements, and to determine the reliability of evidence from witnesses. Bloodstain pattern analysis (BPA) recognizes three types of stains namely passive, projected or impact, and transfer stains. Passive stains are drops or blood flow caused by gravity acting on the injured body whereas impact or projected stains are projected through the air thus leading to spatter which can be caused by the cut of arteries which leads to the blood splashing from the victim. Lastly, transfer stains depict the aftermath of the crime, for instance, movement of the victim, the direction (Baker, 2010). Different items and range result in different bloodstains, for instance, gun spatter from entry and at the exit shows the caliber of the gun used. Cast-off violence leads to the blood spreading to the nearby surfaces which is essential in determining the angle and a minimum number of blows delivered (Baker, 2010). These patterns differ based on sharpness, surface area, and blunt force injuries and the force used. Therefore, photos of the bloodstains patterns help investigators in recreating the crime.

Although bloodstains are the most used biological evidence in crime scenes, other fluids such as semen, saliva, urine, and vomit among other body fluids have been used in forensic investigations. In most sexual abuse cases, semen is used to determine the perpetrator of the crime. Saliva and vomit tend to be contaminated depending on the type of food consumed and the time of the day. Other biological evidence includes hair, fingernails, body tissues, bones, or organs. The extensive use of other biological evidence broadens forensic investigations.

References

Baker, L. (2010). Review of:Forensic Biology: Identification and DNA Analysis of Biological Evidence.  Journal Of Forensic Sciences ,  55 (1), 281-281.

Catalin, M., Andrei, A., & Mitrasca, O., (2015) Modern Methods Of Collection And Preservation Of Biological Evidence For Human Identification By DNA Analysis . Retrieved December 5, 2018, from https://www.abacusdiagnostics.com/Modern_Methods_of_Collection.pdf 

Question 2 

The collection and storage of bloodstains are vital in DNA typing. DNA typing includes polymerase chain reaction (PCR), short tandem repeat (STR), Y-Chromosome, and mitochondrial analysis. PCR is the use of an enzyme to replicate DNA regions in a test tube. It involves replicating the DNA molecules to increase the increase the molecules which are vital in increasing the molecules of skin cells. On the other hand, STR analysis is the use of 13-loci DNA profile that helps determine a victim or perpetrator of the crime (NIJ, 2012). Therefore, if blood is collected in liquid form, it should be stored in test tubes and refrigerated to mitigate the deterioration of the bloodstain properties essential in DNA typing. The 13-loci DNA profile is different for individuals thus making it easier to determine the exert victim or perpetrator of a crime. The y-chromosome analysis uses the Y-chromosome markers to target male thus enable the use of fathers or sons to trace the likely family of the victim or perpetrator. The lab extracts and separates the vaginal cells from the semen for this analysis. Lastly, a mitochondrial analysis is used in investigations whereby the evidence lacks nucleated cells for instance, where biological evidence such as teeth, bones, and hair are used (NIJ, 2012). The collection, preservation of evidence, transportation and storage of evidence should eliminate all the likely contaminations as earlier in bloodstain evidence handling.

The Combined DNA Index System (CODIS) is a platform that stores DNA profiles of convicts at the state and federal level used by the FBI. The FBI uses CODIS to match or search for any potential matches of a current crime to another in the past. The investigators can use such random searches to match and investigate a case that had no witnesses (NIJ. 2012). The CODIS is also important in identifying serial killings with the evidence corrected matching the evidence of past crime scenes. These matches have in the past been used to prove the innocence of people prosecuted for the crimes. For instance, Lynn Dejac convicted and jailed for life with a mandatory 25 years in 1993 for murdering her 13-year old daughter was exonerated after DNA evidence demonstrated that she did not stab her daughter in 2007. The DNA evidence demonstrated that Donohue’s DNA was found in Chrystallynn’s, Dejac’s daughter, beddings at the time of death. It was no happy ending as Donohue had signed an agreement exempting him from prosecution of the murder when he agreed to be a witness that led to Dejac’s imprisonment. However, Dejac was a free woman thus demonstrating the value of DNA evidence (Staba, 2007). DNA evidence has also been used to convict criminals. For instance, in the People v. Miles case, scientists at Cellmark Diagnostics were able to connect five crimes with Miles DNA and fingerprints (Longmire, 2004). The Appellate Court upheld the ruling of the State Court leading to his conviction.

According to Shelton (2012), DNA evidence at trial is only admissible if the expert only relays the events as they happened rather than trying to use the evidence for litigation purposes. That is the expert should describe all the scientific evidence and their meaning but should not try to offer any advice to the jury or the court. Therefore, DNA evidence is admissible in court if it uses empirical data that forms a database for identification testimony with almost a 99% degree of certainty (Shelton, 2010). This argument is depicted in the People v. Gary Leiterman. Gary accused of killing Jane Mixer after his DNA was taken from Mixer’s piece of pantyhose while the DNA of a John Ruelas, a man who murdered his mother in 2002, a bloodstain was found on Mixer’s hand in 1969. The investigators argued that it was unlikely that John Ruelas was guilty because he was 4-years old at the time thus making Gary the only suspect (Wixted, 2016). The court should have termed the DNA evidence as inadmissible because it was contaminated thus should not have been used to convict Leiterman.

References

Longmire, A., (2004, October). Landmark DNA Court Cases. Worcester Polytechnic Institute. Retrieved December 5, 2018 from http://www.ric.edu/faculty/lmsm/Landmark%20%20DNA%20Court%20Cases.pdf 

NIJ. (2012, August 9). DNA Evidence: Basics of Analyzing | National Institute of Justice. Retrieved December 5, 2018, from https://www.nij.gov/topics/forensics/evidence/dna/basics/pages/analyzing.aspx

Shelton, D., (2010) Forensic Science Evidence and Judicial Bias in Criminal Cases. Judges Journal 49:3.

Staba, D., (2007, November 29). DNA Evidence Frees a Woman Convicted of Killing Her Daughter. Retrieved on December 5, 2018 from https://www.nytimes.com/2007/11/29/nyregion/29mother.html 

Wixted, J., (2016). Whether Eyewitness Memory or DNA, Contaminated Forensic Evidence Is Unreliable. Association for Psychological Science. Retrieved December 5, 2018 from https://www.psychologicalscience.org/observer/whether-eyewitness-memory-or-dna-contaminated-forensic-evidence-is-unreliable 

Question 3 

Computer evidence follows the following procedures in evidence collection namely; visual inspection, forensic duplication, media examination, and evidence return. Visual inspection entails the determination of evidence, conditions, and relevance of the information before beginning the other steps. Therefore, the officer to keep the computer running because there are high risks of destroying or losing the data if the computer shuts down. Therefore, maintaining a powered on computer is the first step and necessary in collecting volatile data which included running processes, passwords in clear text, instant messages, IP addresses, and other executed console commands. The officer is also able to determine the person who logged into the system, gather registry information, attached devices, and system information which are lost after shutdown. Forensic duplication entails duplication of the media and using the forensic copy to examine the evidence to limit contaminating the original data. Media examination is testing the applications such as the RAM and hard drive. Lastly, evidence return is to secure the evidence safely.

Investigators correcting data target both visible and latent data. Visible data is data recognized by the system whereas latent data is unknown to the system because it is not referenced in the file allocation tables. The investigator reviews the history from the RAM while media usage is copied from the hard drive. Other areas that information is retrieved include the browsers where history and bookmarks are used to understand whether the crime was premeditated by the perpetrator. Documents, downloads, files, video, emails, and network connections are retrieved for the investigation. Computer evidence has been used to solve pedophile, fraud, and cybercrimes but can also be used for other criminal cases. For example, the BTK killer, Dennis Rader, was arrested after taunting police by asking them whether he could use a floppy disk without being traced back. The police used his naivety to arrest him when he used the floppy disk and sent it to a local TV station (Hansen, 2006). BTK killer was arrested after the police traced back the computer at his church leading to his arrest and conviction for 10 counts of first-degree murder.

Mobile phones are also known as cellular telephones that became the most used form of communication in the late 1990s. Smartphones are also included under mobile phone in the digital forensics. The use of mobile phones and the increase of storage memories makes it essential for forensics to retrieve data from mobile phones. However, challenges for such activities involve the complexity of carriers and manufacturers, power and data connectors, the operating systems, security mechanisms, and data preservation. The increase of manufacturers and service providers makes it difficult for analysis to retrieve data without risking data loss or contamination, some of the mobile phones are complex and require the investigators to ensure no incoming call or messages or network connection because such factors would lead to deleting other records (Curran, Robinson, Peacocke & Cassidy, 2010). The physical and logical properties mostly stored in the SIM card are mounted via the smart-card reader to a PC to access the SIM card via GSM SIM access. The mechanism enables the retrieval of binary data which is transferable to the PC but only after the authentication.

References

Curran, K., Robinson, A., Peacocke, S., & Cassidy, S. (2010). Mobile Phone Forensic Analysis.  International Journal Of Digital Crime And Forensics ,  2 (3), 15-27.

Hansen, M., (2006, May). How the Cops Caught BTK: Playing to a serial killer's ego helped crack the case. ABA Journal Retrieved December 5, 2018 from http://www.abajournal.com/magazine/article/how_the_cops_caught_btk/ 

Question 4 

According to Lentini (2013), all fires are termed as accidents. He states that arson is only investigated when fire scenes contain suspected materials such as ignitable liquid residues (ILRs), footsteps away from the fire scene. The investigators must review all fire scenes after the fire is put off by the firefighters. Undertaking the investigation of the fire scenes begins when the firefighters are still putting off the fire with the investigators seeking to identify potential witnesses (Lentini, 2013). The firefighters can note smell or the source of the fire to determine whether the fire was started intentionally. Starting the investigation immediately reduces contamination of the evidence.

The motive of committing arson may include the need to hide evidence of murder by destroying evidence of the victim’s dead body, vandalism, and revenge. The latter two are the most cited motives of fires. The evidence is collected from the fire scene involves reviewing the debris making it easier to determine the source of fire, for instance, the remains or patterns in the place the ILRs was started. In a carpet, the source is not as burnt as the sides of the carpet (Lentini, 2013). Glass or window panes are reviewed to determine whether they were caused by the hit from the fire or before the fire. DNA evidence such as bloodstains is analyzed to determine the carbon dioxide levels with high carbon dioxide depicting that the victim died from the smoke fumes whereas low carbon dioxide means that the victims were murdered before the fire.

Explosive is divided into three main categories namely low and high explosives and blasting agent. Low explosives deflagrate or burn when unconfined whereas high explosives detonate with No. 8 blasting when unconfined. Blasting agent is made from fuel and oxidizers but can detonate although they are not explosive. The fire first responders must engage in safety measures that involves not touching anything they do not know and seeking help from experts in such situation to prevent the risks of death.

Reference

Lentini, J. (2013). Evidence Collection at Fire Scenes.  Encyclopedia Of Forensic Sciences , 387-391.