"In a sane country, finding a person who was murdered should be easy especially when a nearby camera picks up the person from far at least these things are done in Hollywood movies". These are words from a friend of mine who was talking about a case of a person who was murdered some years ago, and it took a while before the police were able to get the killer. The good thing about it is that he was sentenced but my friend was so much concerned about the time frame at which the case took to get resolved.
I mentioned to him that while it might be faster in the West, it isn't as always fast as these movies portray them and this is because for the directors of the movies, going through the process in actual real time can be boring so they decide to take theirs a bit faster than reality but if this was to happen in real time, what would be the process.
This process to always identifying this type of scenario is known as Forensic which is the use of science in law especially criminal law. People who do this can have degrees in scientific field including biology, chemistry, medicine, and forensic science. So that said, let's use the scenario above where a person was murdered and the police are called in as well as forensic experts to pick up details needed before the body is moved from the area.
When they get to the area, they first take a look at the body because, first they want to be able to identify the person as well as the time of death of the person. If the wallet of the person is found with an ID of the person's detail, as well as a teller receipt from an ATM machine as well, then it is easy to identify the person. If the teller from the machine is about 6 hours ago, it means the person was alive about 6 hours ago.
To know how long he was dead the examiners will use certain medical studies on the body change of state after death. First, they check if the body is still at Livor Motis which is a state of the body where the blood flows and settles anywhere gravity pulls. This is because the heart is no longer pumping blood, making the body purple. If the blood is still liquid and pulls towards gravity, it means the person died less than 12 hours ago which is the case of the person in this scenario because after 12 hours, the blood begins to coagulate and dry and with this, the blood will not pool to an area where gravitational force is pulling it to when moved or shifted. With this, it is certain that the death is less than 12 hours.
Another thing medical examiners will check is Rigor Motis, which is the stiffening of the muscles of the body after death. The body expends a lot of energy to keep the muscles relaxed but when a person is dead within the first 2 to 36 hours, the muscles do not have the energy to make the muscle relax, so the muscles stiffen until the muscles begin to breakdown that they cannot hold themselves together. This all shows that it is still within the range of 6 hours which is within the period of when he withdrew from the Automated Teller Machine judging from the teller at hand to when the body was found.
Another way to find the average time of death is measuring the body temperature. After measuring the temperature, the body sits at a temperature of about 29 degrees Celsius. The average living human body has a temperature of 37 degrees Celsius and when a person dies, they lose 1.5 degrees of body heat per hour. So investigators can ascertain that the death occurred not quite long after the ATM cash withdrawal.
Since it is a banking area, there are going to be CCTV cameras around, and upon requesting for the footage of the camera from the ATM machine as at 6 hours ago. Upon replaying the tape, a person was seen with the man at the ATM stand and the camera was able to pick the face in blurry view because of the pixel of the camera but other cameras around the banking area were able to pick the cloth the person wore as well as an axe the person was holding and on the body of the deceased, there is an Axe cut.
In comparison to Hollywood movies where you see that they zoom the camera to see the person's face after which it becomes clearer and they are able to search for the person in the available data base of people, in reality, it is a different case. When you zoom in on a blurred vision, it will become more blurry as a result of the pixel of the camera, also, the security agencies will have to utilize data from the Department of Homeland Security (DHS), Department of Housing and Urban Development or any other form of ministry or department is responsible for collecting the data of people for national identification or census being used depending on country.
Going forward, the investigator has found the suspect and they decided to check his house where they found a Axe with red stain. Red stain doesn't ascertain blood, so they need to find out if it is blood or just paint. Unlike movies where they spray a liquid to detect if it is blood, in reality, they take a swab of the red substance and run a Kastle Meyer Test to find out if it is blood. To do this, they add phenolphthalein and hydrogen peroxide to the swab. If the substance is blood, the compounds will react together to give a pink color. If it isn't blood, then the reaction will not happen because there will be no catalyst to aid the reaction. Once the swab turns red, they take the Axe for testing in the lab for DNA comparison with the victim using the STR Analysis. If the DNA on the weapon matches with that of the deceased, then the murderer has been found.
If we are to be sincere, it is a fun procedure so I wonder why movie script writers and directors do not show these parts but either ways, that's just how science is used in the case of forensic for solving some murder cases.
Reference
https://www.usccr.gov/news/2024/us-commission-civil-rights
https://www.ncbi.nlm.nih.gov/books/NBK549867/
https://www.ncbi.nlm.nih.gov/books/NBK554464/
https://pmc.ncbi.nlm.nih.gov/articles/PMC9375749/
https://www.sciencedirect.com/topics/medicine-and-dentistry/algor-mortis
https://bio.libretexts.org/Bookshelves
https://www.wicell.org/short-tandem-repeat-str.cmsx
