A forensic investigator works with police departments to solve crimes. Becoming a forensic investigator usually requires a bachelor's degree in biology, chemistry, or a related field. Alternatively, having a couple of years of education and some experience may also be enough to get a position in this field.

The first thing that a forensic investigator does at a crime scene is to create a sketch of the scene, including the victims, evidence and anything else crucial to the set-up. This process requires an investigator to determine what the crime was, and then create a drawing of the crime scene as close to scale as possible. This drawing, in addition to the crime scene photographs, is used to help record the original state of the crime scene for investigative and court purposes.

After determining the crime and drawing a sketch, the next step is for the forensic investigator to collect any evidence that may be a part of the crime scene. This is a complicated process. Some crimes have evidence spread over miles of territory. Other crimes involve microscopic evidence, such as DNA or clothing fibers.

Once a forensic investigator collects the evidence, it is carefully bagged, sealed, and recorded. This starts the chain of custody, which is used to keep a record of where the evidence is at all times. The investigator then begins to formulate a hypothesis about how the crime took place and how the evidence points to that theory. This will help lead investigators to a suspect, or group of suspects, and will eventually solve most crimes.

Forensic investigators work in a very physically, emotionally and mentally draining field. There is a lot of heavy lifting and potential danger. They need to pay very close attention to even the smallest detail of a crime scene. Investigators use advanced technology to find and recover the tiniest pieces of evidence. This includes fingerprints, blood and other bodily fluids, and trace evidence. They will use trajectory analysis to determine the path of a bullet, along with where and what the bullet was shot from. They will also need to make castings out of impressions, such as footprints or tire marks, left at the scene of the crime.

When a forensic investigator is not investigating crime scenes, she may be found filling out paperwork or testifying in court. The work of a forensic investigator is often done as part of a team, especially in larger police departments. Smaller departments might share one or two forensic investigators amongst themselves.