There are a number of things that a person will have to do in order to become a crime scene investigator. A college education is necessary, and a degree in a physical science is usually preferable. Crime scene investigators usually have to be police officers as well, though lab analysis may be done by private contractors. Regardless of the rules in your particular area, there are some certain physical characteristics that are necessary for anyone to become a crime scene investigator.
One of the most important characteristics of a crime scene investigator is physical endurance. Crime scenes can take hours to process thoroughly, and in some cases, they have to be gone over with a fine-toothed comb to find all of the evidence. Like many police officers, crime scene investigators will have to put in a good amount of overtime to get the job done right and to make sure all evidence is properly collected, transported and analyzed so the information can be given to the detectives working the case.
Often crime scene investigators will have to manipulate small or delicate objects without damaging them. This is true both when it comes to collecting evidence at the scene of a crime and when it comes to analyzing evidence in a lab. Manual dexterity is also important to make sure crime scene investigators can properly use some of their equipment, which are often simple tools such as Q-tips and chemical sprays that are only as effective as the person who's using them.
While it's important to have the proper knowledge, desire and willingness to do the job, crime scene investigators are often exposed to some of the most vile, disgusting and outright horrendous things people can do to each other. These investigators often have to pick through garbage, human waste and other substances. Additionally they'll be exposed to murders, sexual crimes, deviant acts and things that may make them both physically and psychologically ill. A person's ability to accept what happened and to move through it to get the job done is an amazing quality that a crime scene investigator will definitely need.