Basics of a Criminal Investigation

A criminal investigation can be broken down in to two fundamental parts; the statements from all parties involved and the physical evidence. It is important to remember that conducting a criminal investigation can differ as much as the people involved. However, police have developed guidelines that are consistently use when crimes are reported. Although it is not all encompassing, the generalities hold true and can be extrapolated to fit the needs of the individual case.

Upon arriving at a site of a criminal complaint an investigator must put themselves in a position of objectivity. There are three sides to every story. There is the suspect's side of the story. There is the victim's. And there is the truth. The truth, more often than not, lies somewhere between the victim's version and the suspect's version. This depends a lot of the relationship the suspect and victim have. If they know each other, the truth is close to half way between their statements. If the victim and suspect do not know each other, the victim's account is usually the most accurate. While this doesn't always hold true, ten years of law enforcement have shown me this is the case more often than not.

Ultimately the best person to speak with is an uninvolved witness. A bystander usually has nothing to gain or lose from the situation. If all the adults present during the event have apparently taken sides, children are a good source for the truth. Every human has a basic understanding of right and wrong. Children, who are willing to lie for their parents, will generally tell the truth if questioned prior to coaching from adults.

It takes years to learn successful interview skills. There are a few simple techniques that are easy to learn that can help get to the bottom of things. To begin with, don't start by confronting your interviewee immediately. It is important to get them talking. A confrontation may shut them down and make it difficult to open a dialogue. Start with simple easy questions he or she knows you know the answer to. Basic information is a great place to begin. Ask their name, birthday, address, etc. After a little small talk, ask them what happened. Get them locked into a story. Take what you know what happened and slowly start ask specific details. Ask the same questions in different ways throughout the interview process. Pay attention to smallest facet. The more a person needs to lie, the harder it will be for them to remember what they told you. A person telling the truth will easily reiterate the same points when pressed. If you catch your interviewee in a lie, let him know subtlety. Say something like "that doesn't make sense" or "that it isn't consistent with what you said before". Once they lie, it is easier for them to admit they are lying about other things. Criminal psychologists believe that most people want to tell the truth, if nothing more than to get it off their chest. Plus, a small lie gives you a foundation to not believe them. Saying' "You already lied to me before," is a powerful statement when trying to solicit the truth.

After the interview is over, it is time to examine the physical evidence. A properly trained evidence technician must go through and evaluate the scene. Prior to any seizures, the evidence tech must document everyone who has entered and exited the area just after his or her arrival. Other officers, witness, medical or fire personal as well as the evidence technician themselves contaminate potential clues. If the contamination is taken into consideration and properly documented, then the evidence will still be of value. Each item seized must be accounted for in a chain of custody. In order to prevent any claim of tampering an evidence officer must account for time, place, and persons handling any given article.

Most courts require police and prosecutors to abide by the rule of "best evidence." Simply put, best evidence means it is better to present an article itself, when possible, as opposed to a reproduction. For example, if police recover a bullet casing, the best evidence is to produce the casing itself in court instead of a photo. It gives more credibility to the evidence. Of course photos have their place. It would not be practical wheel a dead body into a court room to show injuries despite the rules of best evidence.

Evidence is sent to a laboratory for examination. Items like fingerprints and DNA are extracted matched against police databases while tire prints or shoe prints are analyzed to determine the likelihood they were created by certain respective vehicles or footwear. Once the lab completes its analysis, the results are sent back to the reporting agency.

It is then up to the investigators to determine whether or not the statements given by the parties involved are consistent with the conclusion one would draw from the physical evidence. For example, a murder suspect claims he wasn't near the victim when the victim was shot. If the victim's blood was discovered on the suspect's clothes, the suspect's statement is conflicting with the physical evidence.

In the end no one will ever know exactly what happened expect the people who were there. Criminal law requires proof beyond a reasonable doubt for a conviction based on the evidence presented. A prosecutor once explained to a jury that reasonable doubt was like doing a jigsaw puzzle of a cat. All the items in evidence are pieces. If you put the puzzle together can you still be sure it is a cat even though pieces are missing. Essentially, investigation is a matter of finding all the pieces available and put them together to best of the investigator's ability.