How is DNA physically collected? What’s revealed? How is it matched to a database of people? And how are samples collected without contamination?
In: Biology
We leave our DNA absolutely everywhere, whether we intend to or not. A skin cell or a microscopic drop of blood or saliva contains your entire genome. Crime scene technicians swab and sample absolutely everything at crimes scene, especially obvious things like blood stains, in the hopes of picking up some DNA. They go through great trouble to avoid contamination. That means using sterile equipment, collection tools, and wearing things like gloves, surgical masks, and even shoe coverings to prevent contamination.
Once collected, it’s put through some chemical processes in a lab that will identify if there’s any DNA present, and if so, sequence it into a readable form. People arrested and/or convicted of certain types of crimes (depending on the country) will have their DNA stored in a database. If there’s a match, you know it’s that person. If not, police will have to try and obtain the DNA of suspects to look for a match. Recently, police have been able to match DNA collected at crime scenes to the suspects by finding their family members on DNA testing services like 23andMe.
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