One-on-one allegations are very common in criminal investigations. The accuser may be an alleged victim. The accused, of course, denies involvement and offers an explanation for the false allegation. In other situations, an incident occurs and there are only two possible suspects. Obviously, both suspects will name the other as being the guilty party.

These "He said, she said" cases are inherently difficult to investigate for a number of reasons. Often, there is not a clear separation between a truthful and false account. That is, both parties may be telling part of the truth and also omitting or embellishing information. In many cases, these interviews are conducted when one or both parties are in an emotional state of mind which can cause misleading behavior symptoms. Finally, because these cases are often spontaneous, a decision to make an arrest must be made without the benefit of conducting an interview in a controlled environment. This web tip will offer suggestions to help assess the credibility of the people involved in one-on-one allegations.

1. Question both parties separately.

There is no better illustration of the problems associated with having both the accused and accuser present during questioning than on television court shows such as, "The People's Court" or, "Judge Judy." Invariably, the liar becomes more committed to his or her position and rarely confesses even when confronted with evidence. The truth-teller may become angry or reticent out of frustration and staunchly face the judge with his or her arms crossed. Suffice it to say, to learn the truth requires that both accused and accuser be questioned separate from each other.

In a domestic violence case involving a husband and wife, for example, one investigator could question the wife in one room while another investigator interviews the husband in a separate room. In a traffic stop, one occupant may be left in the vehicle while the other is questioned away from the vehicle. Following the initial interview, the first occupant could be asked to wait in the vehicle while the second is questioned away from the vehicle.

If the interviews are conducted by the same investigator at different times, it is beneficial to first interview the accuser and then the accused. If two possible parties to a crime need to be interviewed, the person most likely to tell the truth, or least likely involved, should be interviewed first. This assessment may be based on age, strength of evidence, as well as behaviors or attitudes displayed during initial questioning.

2. Consider having both parties write out a statement.

In a controlled environment, such as a business where an employee is making allegations of unwanted sexual advances against a supervisor, it is often beneficial to not only question each party separately, but also to have each party first write out a statement. This suggestion applies equally well to any one-on-one allegation where both parties are in a controlled environment.

To obtain the statement the investigator should give the suspect a couple of sheets of lined paper and pen. At the top of the paper the investigator should write out a question which he instructs the person to answer in writing. The question should require that the person explain everything about their behavior, knowledge or observations. The following are possible introductory questions to ask in different situations:

Domestic violence: "Tell me everything about what happened between you and your husband (wife) this evening."

Sexual harassment (complainant): "Tell me everything about what you experienced at (Company) that led to your complaint."

Sexual harassment (respondent):"Sally Smith reported that you made sexual remarks to her. Tell me everything about any sexual remarks you have made to Sally Smith."

Gun found in dorm room: "Tell me everything you know about the 9mm gun found in your dorm room last Friday night."

Hit and run with two possible drivers: "Tell me everything you know about the damage to the front right bumper of your room mate's car."

While it does take extra time to obtain a written statement (most of these, even from truthful subjects, are only a couple of paragraphs long) there are a number of benefits. First, the statement can be assessed for credibility by applying statement analysis techniques. Second, information from the statement can help the investigator prepare for a formal interview of a suspect in that he knows what topics to cover and may have identified problem areas within the statement to pursue. Finally, because the statement is a permanent document from the suspect, any documented lies or inconsistencies can be used to support decisions relating to the case disposition.

3. Obtain behavioral information from both parties.

It does the investigator little good to learn that a husband yelled at his wife and scared her. To assess credibility, the investigator must develop behavioral information. Behavior is objective and fixed in time. It is not subject to justification, rationalization or individual interpretation. The investigator needs to find out specifically what was done, who was present, what object was used, where something happened, what was said, etc.

While it is certainly more efficient to ask questions that require a yes or no response such as, "Did your husband threaten you with a weapon of any kind?" or, "Did your husband strike you at all?", these closed-ended questions can invite deception. Especially during early portions of an interview, the investigator should ask open-ended questions that require a narrative response. This approach is much more likely to result in truthful information as the following dialogue illustrates:

I: "What happened here this evening?"

S: "My husband came home drunk and starting yelling at me and accusing me of cheating on him. We argued and he threatened me. I was scared for my life. That's when I called 911."

I: "Tell me how he threatened you."

S: "He was yelling and calling me a bitch, and he said I would pay for what I did."

I: "Tell me about any physical contact he had with you this evening."

S: "Physical contact? He got right in my face and was yelling and threatening, like I said."

I: "So he did not have physical contact with you this evening?"

S: "No, but I think he was going to."

I: "What did he have in his hands when he was arguing with you?"

S: "Well, nothing. But his voice had a threatening tone."

If two investigators are simultaneously questioning the accused and accuser, it is much easier to establish what really happened if both investigators focus their interviews on behavioral information. When the two investigators compare notes, they can identify which behaviors both parties agree upon, and which behaviors are disputed.

4. Suggested behavior provoking questions

The unique dynamics of one-on-one interviews present the opportunity to ask a number of behavior provoking questions that may be helpful in determining which party is telling the truth. One of these is a BAIT question where the subject is asked, "If (accuser) was given a polygraph examination concerning the statement that you pointed a knife at her this evening, what would her polygraph results be?" An innocent suspect typically predicts that the accuser will fail the polygraph. On the other hand, the guilty suspect will not have that level of confidence and may offer an evasive response, e.g., "I don't really know much about polygraphs" or perhaps even predict truthful results, "She's a really good liar n she might be able to beat a polygraph." As a legal aside, an employer is not in violation of the 1988 Employee Polygraph Protection Act by asking an employee how another employee would do on a polygraph.

A second behavior provoking question is the CREDIBILITY question. It is simply phrased, "When (accuser) says that you (did issue) is he/she lying? e.g., "When Sally says that you forcibly pulled down her jeans and underwear, is she lying?" It is very difficult psychologically for a person who knows that the accuser is telling the truth to respond to this question with a confident agreement. A deceptive suspect may offer a qualified response, "I believe she might be, yes." or an evasive response, "I know what happened, and that's all I can say."

In the controlled environment of a laboratory study, one-on-one allegations are the easiest type of case to solve. By design, one subject is telling the truth and, therefore, the other subject must be lying. In real life, however, these cases are often not cut and dried because the subjects' behavior is contaminated by numerous outside variables including intense emotions, intoxication of one or both parties, and the telling of partial truths. An important key in assessing the credibility of parties involved in a one-on-one allegation is to interview both parties separately and focus the interview on specific behaviors, not opinions or judgments. In a controlled environment, requesting that both parties respond in writing to a central question can be beneficial both in making an initial assessment of credibility as well as conducting a subsequent interview.