Factual analysis can be defined as estimating the probability of a suspect's guilt or innocence based on investigative findings. Each investigator uses factual analysis to narrow the scope of suspects - to eliminate innocent suspects and to focus the investigation around a particular suspect most likely to be guilty.

As an introduction, factual analysis is divided into five component parts: Opportunity/Access, Attitude, Motivation, Biographical Information, and Evidence.

Evaluating Opportunity/Access

One of the first determinations of factual analysis is whether or not the suspect had to be physically present to commit the crime, or if the crime could have been set up in advance, such as a fire started with a timing device. In other circumstances, it is possible that the guilty person hired someone else to commit the crime. Opportunity refers to the suspect's physical presence at the time of a crime. If a suspect was not present at the time a crime was committed, and the crime could not have occurred without the offender being present, he must certainly be innocent. If a suspect claims to have an alibi, he is essentially denying possible opportunity to commit the crime. Testing the veracity of an alibi is, therefore, critical to factual analysis because, in cases requiring opportunity, if the alibi is correct the suspect can be eliminated. Conversely, if the alibi is false, there is a high probability that the suspect is guilty. Only on rare occasions will a suspect who has lied about an alibi be innocent of the crime under investigation. One such occasion is when the suspect's true alibi is embarrassing (being with a prostitute), or perhaps when the true alibi involved a different illegal activity (burglarizing an apartment).

Alibi witnesses used to corroborate the suspect's lack of opportunity must be carefully scrutinized. If the witness is a family member, friend or relative who would have a motive to protect the suspect, obviously the alibi is weaker than if the witness was someone not personally acquainted with the suspect (a dentist, gas station attendant, sales clerk, etc.). Apart from a loyalty motive, the investigator should keep in mind three other motives for alibi witnesses to lie. The first is the witness who is being blackmailed by the suspect, the second is, the witness who is being physically threatened by the suspect, and finally, the witness who is an accomplice with the suspect in the crime.

Access refers to special means or knowledge needed to commit a crime. Some crimes involve very special access such as knowing the victim, possession of certain keys, knowing the combination to a safe, working a cash register, knowing how to turn off a burglar alarm, possessing a gun, or having access to a pickup truck. Certainly some crimes have a lower access requirement than others. It is important to remember that a guilty suspect not only must have an opportunity to commit the crime, but must have the necessary access to commit the crime as well.

As a general rule, the better access a suspect has to commit the crime, the more likely he is to be guilty. Therefore, if a theft of money occurred from a vault, the most likely suspects are those who work in the vault area. If a washer/dryer was stolen from a loading dock, loaders who work in the warehouse and have access to a large vehicle are more likely to be involved in the theft than warehouse employees who commute to work on the bus, or salespeople who do not work in the warehouse.

When evaluating access it is essential to establish the modus operandi of the crime. In the theft of the washer/dryer example, could an employee have filled out a false transfer sheet so the loaders would put the machines in the company truck and then the dishonest employee drove the truck to his home? In this case no personal vehicle is required. In a theft from a safe, the typical access requirement is a combination. However, the investigator must be certain that the employee who claims to have locked the safe is 100% certain he did not accidentally leave it open and, also, that the combination was not written down and discovered, or released to unauthorized individuals.

Evaluating Attitude and Motivation

Each criminal act fulfills a specific need. These needs can roughly be divided into three categories: real needs, lifestyle needs, and psychological needs. From factual information, oftentimes the motive of the crime can be identified. While determining the motive of the crime can be a useful adjunct for factual analysis, it plays a bigger role in the interrogation of the guilty suspect.

A real need threatens the suspect's livelihood or physical well-being (primary needs). The suspect who steals because he has received an eviction notice from his landlord, or because his bank has threatened to repossess his car is stealing for a real need. Similarly, the suspect who kills a man who has been blackmailing him, or a loan shark who threatens the family, has killed for a real need. Suspects who kill or steal to maintain a drug or gambling habit are also committing real need crimes since the antisocial behavior is addictive in nature and threatens the suspect's physical or psychological health.

The second category of criminal motivation describes crimes that are committed to maintain an elevated financial or social status. Under this circumstance the crime is classified as fulfilling a lifestyle need (secondary motives). Examples of lifestyle needs would be purchasing a home or car beyond one's needs or overextending one's credit through purchasing extravagant clothing, jewelry, or furniture. While many lifestyle needs are achieved through theft crimes or selling drugs, the investigator must consider espionage, arson and homicide under this category as well. The property or individual against whom the crime was committed may have threatened the suspect's lifestyle and therefore was eliminated.

The final category of motives describes psychological needs. These typically satisfy stimulus motives. As a general statement, the psychological needs that are fulfilled through criminal behavior can be thought of as either impulse or esteem motivated. Crimes committed out of impulse needs tend to be emotional in nature and result from an uncontrollable emotional state -- typically anger, hatred, revenge, or fear. Homicide, rape, and arson can each be impulsively motivated.

With respect to esteem-motivated crimes, these suspects are typically demonstrating their superiority or influence over their victim through a criminal act. Many suspects who commit crimes to satisfy an esteem need will be diagnosed as suffering from an impulsive personality disorder.

Biographical Evaluation

Biographical information, such as a suspect's age, race, gender, education, marital status, living situation, and social status may enter into the factual analysis formula. The following guidelines offered with respect to biographical assessments are either from crime statistics or repeated empirical observations.

AGE: Younger suspects are more likely to engage in spontaneous, opportunistic crimes than older suspects. Middle age or older suspects tend to commit crimes that are more premeditated unless, of course, the crime was impulse motivated. The bold robbery that occurs in broad daylight is almost always committed by a young man, whereas a carefully planned embezzlement scheme is more typical of the older person.

As most individuals become older their attitude toward honesty increases as does their level of social responsibility. Therefore, when comparing three suspects, ages 18, 30, and 40, suspected of employee theft, the 18-year-old is most likely guilty and the 40-year-old least likely to be guilty (provided all other factors are equal).

GENDER: Women tend to be less bold than men in their criminal behavior. Women also tend to commit crimes to satisfy a perceived real need and are more likely to commit crimes that help out another person than do men. Esteem-motivated crimes are typically perpetrated by males. Males are more likely to steal larger amounts at one time than females. Therefore, a theft of a $5,000 deposit is more typical of the male, and an embezzlement where $500 was stolen every month for a year is more typical of the female. In addition, crimes of violence (strong armed robbery, assault, battery) are much more characteristic of the male simply because of the male's relative strength. However, women are just as likely as men to commit crimes of passion.

RACE: In crimes directed toward a human victim, interracial differences are rare. Generally, whites rape whites and blacks rape blacks. When interracial crimes are committed, there is usually a logical reason for the interracial characteristic, for example, a white killing a black because of racial prejudice.

MARITAL STATUS: Single suspects are more likely to commit crimes than married suspects simply because they have less responsibility toward others, and therefore less to lose if they get caught. In general, married suspects are more stable, responsible, and less likely to engage in criminal behavior. If a married suspect with children and family responsibilities does commit a crime, it is frequently to satisfy a real need. On the other hand, a single suspect is more likely to commit a crime which satisfies a lifestyle need. If a suspect is divorced, the reason for the divorce should be pursued by the investigator, because the marital problems may reveal behaviors which contribute to factual analysis (alcohol or drug problems, battery, infidelity, etc.).

ROLE MODELS: It is a well-established fact that children whose parents smoke are more likely to smoke than children of nonsmoking parents. The same is true of alcoholism, wife beating, sexual abuse, teenage pregnancy and unemployment. Clearly a family history of criminal behavior, violence, or substance abuse enters into factual analysis. The converse can also be stated -- law-abiding parents are more likely to raise law-abiding children. The exception to this rule are adolescents, who may strike out at their parent's attitudes through criminal behavior. This is especially observed when the parent's occupation represents authority or righteousness (police officer, judge, clergyman).

INTELLIGENCE: Suspects of lower intelligence are more likely to commit violent crimes. If these suspects do commit a nonviolent crime, it generally is opportunistic in nature. Suspects of higher intelligence will be less violent in their crimes and are more likely to commit a premeditated, well-planned-out crime. Suspects of lower intelligence are more likely to commit impulse crimes since these suspects appear to have poorer emotional control. If a suspect with higher intelligence commits an impulsive crime, the effects of alcohol or drugs should be considered.

SUBSTANCE ABUSE: Many violent crimes (homicides, rapes, robbery, battery) are committed when the suspect is intoxicated. A suspect with a known history of substance abuse, therefore, should be considered as having a higher propensity to commit these types of crimes.

PSYCHOLOGICAL DISORDERS: Schizophrenics are much more likely to be a complainant than a suspect. Manic depressives are more likely to commit a crime against another person in their depressive phase of the disorder. During their manic phase, they are more likely to commit theft crimes such as obtaining a fraudulent credit card or stealing from a cash register. A suspect with a history of depression has a propensity toward crimes of desperation. Suspects with anxiety disorders are more likely to be innocent if the crime involved premeditation, simply because such individuals would not easily tolerate the anxiety associated with carefully planning out a crime.

Evaluating Evidence

In factual analysis, evidence is given great weight in terms of implicating a guilty suspect. There are two basic types of evidence that can implicate a suspect: circumstantial and physical. Both of these types of evidence have their own strengths and weaknesses and will be discussed separately.

Circumstantial evidence represents documentation of a suspect's opportunity, access, or motive to commit a crime. The significance of each of these areas has previously been discussed and will not be reiterated. Circumstantial evidence is the weakest form of evidence to implicate a suspect. On the other hand, circumstantial evidence becomes especially significant if the evidence contradicts a suspect's previous statement, or appears too coincidental and violates the test of normal behavior within factual analysis.

For example, a suspect who stated that he was in a different state at the time a crime is committed should be considered probably guilty if the investigator documents that the suspect was given a speeding ticket two miles from the scene of a robbery just minutes after the robbery took place. This same evidence does not become nearly as incriminating if the suspect initially acknowledged that he was driving his car approximately a mile from the scene of the robbery at the time it occurred.

Circumstantial evidence relies, to a large extent, on information provided by lay-people. For this reason, the investigator should be aware of biases and blatant misinformation offered by witnesses or victims. In one case, a business partner established a circumstantial case against his secretary. The secretary was apparently the only possible person with access to a stolen deposit. After she was reported as telling the truth following a polygraph examination, the remaining partner of the firm requested that his partner (who reported the theft) also be given an examination. The examination indicated deception and resulted in a confession. The partner admitted returning to the office after hours and stealing the money. He felt confident that the investigation would not find him out because of the circumstantial evidence he provided implicating the secretary.

There are two different classes of physical evidence. One type of evidence relies on scientific techniques to match unknown evidence against a known ground truth. For example, tests identifying cocaine will match chemical or physical properties of an unknown substance against the chemical and physical properties of a substance known to be cocaine. Other types of analysis which would fall within this category are DNA, fiber identification, fingerprints, and ballistics. This type of physical evidence will be referred to as exculpatory physical evidence.

The reason that this term is used is that the evidence generally only demonstrates innocence (the fingerprints do not match the suspect's, the pubic hair is not from the suspect, etc.). When the results of an exculpatory test are positive, standing alone they may support, but do not prove guilt.

For example, assume that a service station notified the police that a vehicle they were repairing matched the description of a vehicle involved in a hit and run accident. Exculpatory tests can demonstrate that the vehicle, in all probability, was the one involved in the accident. However, this evidence, in and of itself, does not mean that the owner of the vehicle is guilty of the crime. An investigation is required to determine who was driving the vehicle at the time of the accident. Similarly, DNA can offer strong support that a suspect had sexual intercourse with a victim, but without statements from the suspect (who may claim that the intercourse was consensual), no definite conclusion about the presence of force can be drawn.

Fact Analysis plays a critical role in the investigation process. The Reid Technique consists of a three-phase process beginning with Fact Analysis, followed by the Behavior Analysis Interview (which is a non-accusatory interview designed to develop investigative and behavioral information), followed by, when appropriate, the Reid Nine Steps of Interrogation.

For a more detailed discussion of Fact Analysis please see Criminal Interrogation and Confessions (5th edition 2013).