What is forensic DNA testing?

Forensic DNA testing is the testing of DNA samples for the purpose of solving crimes. Many crime shows depict forensic DNA testing with the capturing of different samples, such as blood and hair, from a crime scene. Is this an accurate depiction? Well, these samples can be used for DNA testing, but this isn’t the whole story. Forensic DNA testing can actually be done with a variety of DNA samples, and it turns out that this type of DNA testing is extremely accurate. Courts of law and other legal entities trust the accuracy of forensic DNA testing to the point that they will convict someone of a crime based entirely on DNA evidence.

How does forensic DNA testing work?

Before we can test the DNA samples to solve a crime, we must obtain the DNA samples. DNA samples can come from a person’s hair, bodily fluids, skin cells, fingernails, toenails, and bones. It is surprising how many places one can find these samples. Such DNA samples can be found on clothing, sheets, towels, silverware, drinking glasses, used tissues, condoms, eye contacts, band-aids, cigarettes, gloves, tools, abandoned weapons, and more.

To collect the DNA samples, an investigator will go to the crime scene and gather these samples by taking the physical item with them in a sterile container, or by swabbing an item that may contain a person’s bodily fluid, such as a sample of blood or a sweaty door handle. The investigators will work carefully to ensure that their own DNA does not contaminate these valuable samples.

Once the DNA sample is collected, we must compare it to the DNA sample of a crime suspect. The DNA of both samples can be compared for relatedness in multiple ways:

1) Nuclear DNA Analysis

This method of DNA testing is called DNA Profiling or DNA Fingerprinting. With this method, we take the samples of DNA found in the nucleus of a cell from the suspect and the crime sample and compare them to each other. The genomes- all of a person’s DNA put together- are compared side by side. The more similar the samples, the more likely the suspect is the person who committed the crime.

2) Mitochondrial DNA Analysis

This method compares the DNA from the mitochondria of the suspect and the crime scene sample. Mitochondria are present in almost every cell in the body and help the cell produce energy to survive. We are able to use the DNA from this part of the cell for forensic investigations.

3) Y Chromosome DNA analysis

When the suspect is male, we are able to compare the Y chromosome of the suspect with that of the DNA from the crime scene. This method does not work with female suspects since females do not have a Y chromosome. 

Forensic DNA Testing Uses

DNA testing is not only use to convict criminals in court, but also to exonerate innocent suspects as well. Forensic DNA testing can also be used for forensic paternity cases in which paternity must be proven, either for missing person identification or for proving rape or incest cases when pregnancy results. Many alleged criminals have been freed from prison, and even death row, due to their proven innocence from Forensic DNA testing.

If you are interested in Forensic DNA testing, contact us today to schedule a DNA test appointment with the best DNA testing lab in NYC.

References: 

https://en.wikipedia.org/wiki/DNA_profiling

https://dnacenter.com/blog/forensic-dna-testing/

http://www.forensicsciencesimplified.org/dna/how.html