AMU Law Enforcement Public Safety

Using Statistics to Keep an Investigation Focused

Nearly 15, 000 people were murdered in the United States in 2007. Almost 12,000 men and over 3,000 women according to the FBI’s report “Crime in the United States”. The Bureau of Justice Statistics (BJS) reports that the majority of these victims knew their killers. Only 29 percent of men are estimated to have been killed by strangers. The figure for women is even more striking: nearly 90 percent of women were murdered by someone they knew. Only 10% were killed by people they had never met. Further, in cases where the sex of the perpetrator was known, 90 percent of women were killed by men. Investigators should keep these statistics in mind during the course of their homicide investigations particularly cases where the victim is a woman.
When a detective arrives at the scene of a homicide and the victim is a female the perpetrator will very probably be a man she knew. Her body may have been moved or the scene staged to make it appear that she was murdered by a stranger but in nine cases out of ten the killer will be a male with whom she was acquainted – often intimately. The BJS report states that 64 percent of female homicide victims older than twelve were murdered by family members or intimate partners. Therefore, while performing all of the routine steps that are part of any investigation the detective needs to ensure that part of the inquiry proceeds as if the murder was not a random act of violence – because it probably wasn’t.

Detectives should look into casual acquaintances, as well as past, present and potential lovers. They need to ask friends and associates about people she was dating and who may have been pursuing her. If she was married, in addition to her husband, talk to female friends in whom she may have confided if she was contemplating or having an affair. Detectives should interview the victim’s coworkers. Social networking sites are relatively new sources of information. Detectives need to determine if the victim had Facebook, Twitter or MySpace accounts among others. The victim’s postings should be reviewed to see if she wrote anything that could be a motive for her murder. Her friends and contacts listed on these accounts should be contacted because they may know about aspects of her life that her non-virtual friends didn’t.

All of these interviews should take place early in the investigation. The subjects of these interviews, whether innocent or guilty, will be more inclined to provide detailed statements at this stage than they will be later. The innocent subject who knew the victim will be anxious to assist while the pain of her loss is still fresh. If a detective circles back to them weeks or months after the homicide they may be put off that they were not interviewed sooner. The guilty subject interviewed at the beginning of the investigation will provide a detailed statement since it will be part of his strategy to appear to be cooperating with the police.

He may be caught unprepared if he thought his ruse of making the murder look like a random killing would prevent him from being thoroughly interviewed early in the case. It is not acceptable to ask anyone for this type of information weeks or months after the murder once investigators conclude that the crime was not committed by a stranger. An innocent person will not remember in detail his whereabouts and actions with the accuracy he would have at the time closer to the crime. A guilty person will remember exactly what he did but may use the passage of time to feign confusion or forgetfulness. The interviews should establish what each individual’s current relationship was with the victim and his whereabouts at the time of the crime. The investigator must ask probing, detailed questions and appropriate follow-up queries until there is no ambiguity in the subjects’ statements. The investigator has no way to predict what facts will be uncovered in the coming weeks and months of the investigation or what portions of the subjects’ statements will become significant.

Even if the crime appears to be random detectives should conduct a full background investigation of the victim to try to establish a motive or identify who may have wanted to harm her. In addition to interviewing those who knew her detectives should check her financial, phone, internet and email records. Depending on the cell phone model detectives may be able to track the victim’s whereabouts during the last hours of her life. In addition to incoming and outgoing calls the records of the locations of the phone should be requested from the victim’s wireless carrier. This could prove significant when compared to the record of a suspect’s phone. This information along with knowledge gained from the crime scene, witness statements and the autopsy should all be compared to the detailed statements taken from people who knew the victim. This comparison may reveal discrepancies between the statements people gave and the hard evidence the investigator has collected. Some discrepancies are to be expected – nobody’s memory is perfect. But, a cluster of contradictions between the evidence and one subject’s statement may indicate complicity in the crime. He should now be brought back in for an interrogation.

It is extremely difficult for a guilty person to create a statement that fits the evidence. When faced with the detailed statement he made to the police and the evidence that refutes it the subject may see the futility of further resistance and confess. If the investigator is convinced of the suspect’s guilt the interrogation should be presented as an opportunity for the subject to explain why he killed her – since the detective already knows that he did. If the suspect attempts to modify his original statement to fit the evidence he can be confronted with the ultimate no win question: “Were you lying then or are you lying now?” In the absence of a confession the conflicting statements combined with the evidence that confuted the suspect’s original version of events will be a damning set of circumstances.

If a person known to the victim is eventually arrested and charged it may well be based all or in part on a statement he gave to the police. The defense will naturally attempt to have this statement excluded. A statement obtained early in the investigation, when it still seemed that the victim was killed by a stranger, will be easier to defend than it will be if obtained later when the investigation may have focused on the defendant. After an interview early in the investigation the subject will presumably be free to leave and indeed remain at liberty for a considerable period. This demonstrates that the interview was not custodial and that there was no need to issue the Miranda warnings. The investigator will be able to testify that the statement was taken as a routine investigative step. He or she can truthfully state that all of the victim’s friends, acquaintances and intimate partners were thoroughly questioned even though, at the time, it appeared she had been killed by a stranger. And so they should be; even if it appears she was the victim of random violence.

If a crime turns out to be one of the 10 percent that was committed by a stranger the thorough examinations of friends and acquaintances will inoculate the investigation against charges of tunnel vision. Defense attorneys understand that most women are killed by men they know and will be quick to point this out to a jury. Defense counsel will try to portray their client as a scapegoat being falsely prosecuted by an incompetent police officer who focused on the defendant early in the investigation to the exclusion of all others. On cross-examination the attorney will try to highlight all of the likely suspects the police didn’t interview. A detective will be able to blunt this line of questioning with his or her own record of the in depth interviews conducted with everyone connected to the victim. The thoroughness with which he or she conducted the investigation will demonstrate their professionalism to the jury.

A killer may stage a crime scene in the victim’s apartment to look like a burglary or dump her body on the street so she looks like the victim of a robbery. By keeping in mind the fact that 90 percent of women are killed by a man they knew and thoroughly interviewing all of the victim’s friends, lovers and acquaintances a detective can lay the groundwork for a successful conclusion when the investigation ultimately identifies the right person.

By Tim Hardiman


Catalano, P. S., Smith, E., Snyder, P. H., & Rand, M. (2009). Female Victims of Violence. Washington, D.C: Bureau of Justice Statistics.

Federal Bureau of Investigation. (n.d.). Crime in the United States 2007. Retrieved November 09, 2009, from FBI Uniform Crime Report:

Leischen Kranick is a Managing Editor at AMU Edge. She has 15 years of experience writing articles and producing podcasts on topics relevant to law enforcement, fire services, emergency management, private security, and national security.

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