I have always been interested in the details of DNA testing, and I was excited to see that Chapter 7 covers this section. This chapter addresses DNA’s chemical makeup, location, and how it is used to identify a person.
While many sources of evidence are used in an investigation (eyewitness testimony, physical and forensic evidence, surveillance footage), DNA is considered one of the most reliable pieces of evidence. Since each person’s DNA is unique (excluding twins), it is extremely unlikely that two people have the exact same DNA profile. As a result, if someone’s blood is uncovered at a crime scene and that person matches the sample, it is almost certain that the person was present at that place.
“DNA stores biological information and serves as the instruction manual from which we are built” (P. 263, 2018). All living organisms (plants, animals, humans) receive DNA passed down from their creators and, as a result, resemble them. DNA is found inside the nucleus of a cell and exists in the form of chromosomes. Since blood, skin, semen, and saliva all contain DNA, these cells can determine whether or not a person is a match. Once either of these samples has been collected, it is then subjected to DNA profiling. The analyzed regions of DNA contain short tandem repeats (STRs), which are blocks of repeated DNA sequences on chromosomes.
Roy Brown was falsely arrested and sentenced for the murder of Sabina Kulakowsi, a social worker. The main argument that convinced the jury to convict Roy Brown was the testimony of a dentist hired by the prosecution. The prosecution wanted to use bite-mark analysis (with error rates as high as 91%) to prove Roy Brown was the perpetrator. Roy Brown didn’t even have the ability to bite Sabina Kulakowsi because he had fewer teeth than what appeared on her body. However, 12 years later, Brown’s lawyers uncovered additional evidence that strongly suggested Brown did not murder Sabina Kulakowsi. They contacted the Innocence Project, whose mission was to “use DNA evidence to free people wrongly convicted of crimes” (P. 262, 2018). Roy Brown’s DNA proved that he wasn’t the perpetrator, and he was released from prison.
In conclusion, reading Chapter 7 has given me a great understanding of what DNA is and how cell samples can be used to exonerate innocent people. Nearly every human cell has its own unique set of DNA, which can effectively match which cell belongs or doesn’t belong to a person. Roy Brown is one of the hundreds of people who have had their lives restored by DNA testing, which has proven to be a more effective investigation method than outdated practices such as the bite-mark analysis. Hopefully, more investigations will prioritize the use of DNA testing so each case is fairly evaluated and decided on.
Works Cited
Criminal Defense. “Is DNA Testing Reliable in Criminal Cases?” Jennifer Horwitz Law, 16 Dec. 2021, http://www.jenniferhorwitzlaw.com/2021/12/16/is-dna-testing-reliable-in-criminal-cases/#:~:text=Not%20really.,the%20blame%20on%20that%20person.
Shuster, Michèle Author. Biology for a Changing World. W.H. Freeman/Macmillan Learning, 2018.
Mikael La Ferla 