The important opening seconds
What happens immediately following a serious crime is frequently a mystery.
Many standard home things are still in their original positions as if time had stopped, creating the illusion that the horrific event never happened. Investigators take extreme care not to change the initial scene if they lose essential evidence.
The first step is to meticulously document everything as it happens using video, photos, and written notes. Even objects that initially seem unimportant can later acquire new meanings.
This step is crucial because it might be the sole option for cold-case teams to digitally return to the scene years later to find fresh clues.
collecting and evaluating evidence
Information and evidence are gathered and provided to investigators at the crime scene as the forensic investigation progresses—this aids in giving context to direct the pursuit of evidence.
Before placing objects in bags, the crime scene team methodically identifies and “field-tests” them (i.e., testing is performed on-site).
In certain instances, that entails utilizing chemicals and testing kits to find bodily fluids or other residues connected to the crime.
We also employ some extremely advanced torches that can emit a certain kind of light to aid our ability to see hints that would otherwise be undetectable. This mimics the way club lighting could reveal lint on your black clothing.
The most significant crime scene investigators use the scientific approach at this point, putting out theories about what happened and then looking for data that might contradict them.
As new data come to light, old hypotheses are disproven and replaced with fresh ones.
detection of blood, sperm, and other body fluid traces
Various equipment is available on the scene to help forensic investigators identify bodily fluids like blood and sperm.
Since the early 20th century, the Kastle-Meyer test has been used to check for the potential presence of blood.
The suspicious sample is exposed to a drop of phenolphthalein, immediately followed by a drop of hydrogen peroxide. Haemoglobin, a component of blood, can be found using these compounds. There is a significant possibility that the sample contains blood if it changes color quickly.
To determine the presence of semen, a distinct technique known as the acid phosphatase test is utilized, which can find an enzyme released from the prostate gland. A sample of the suspected stain is exposed to a prepared chemical; when the color changes from clear to dark purple, semen is likely to present.