The Investigative Process

Transcription

1 Name The Investigative Process Forensic Science is a versatile and enormously powerful tool in the investigation of a crime. But science alone is not enough to catch criminals. To be successful, forensic techniques must be combined with the knowledge, experience, and intuition of detectives, uniformed police, and civilian experts and administrators. A crime is committed in a cosmopolitan city any member of the local, or even national, population might be the culprit; they may have even fled the county. Investigators need to eliminate potential suspects systematically to cut them down to a manageable list to interview. There is no single way to do this. Criminal records and forensic databases can help identify similar crimes, and perhaps provide a list of known criminals who might be suspects. Also, a forensic investigation of the crime scene can provide pointers. Victims and witnesses of crimes frequently give police valuable information that can lead them to a suspect. Finally, where it appears that nobody saw the crime, publicity and a media appeal can sometimes persuade reluctant witnesses to come forward. 1. List the four ways investigators can compile a list of people to interview as suspects in a crime. Healthy Skepticism Victims and witnesses often provide information about a perpetrator s sex and age, and this can obviously reduce the size of the suspect pool by half or more. However, acting on this information is not as straightforward as it might appear. Witness statements need to be scrutinized, if not skeptically, then with an understanding of their limitations. For example, if a witness states, I saw a woman walk away from the crime scene, then it might seem reasonable to eliminate men from the enquiry. But what if the witness noticed a man with long, blond hair, and assumed he was female? Experience has shown that witness perceptions and memory can be inaccurate in other respects, so when witnesses refer to a 25-year old investigators look for suspects between the ages of 18 and Why should investigators be skeptical of eye witness accounts?

2 Vital Assumptions If witness or victim statements fail to eliminate suspects, investigators need to make assumptions that narrow down the initial field. For example, most crimes occur in the neighborhood of the culprit s home so investigations tend to begin around the crime scene. Local house-to-house inquiries can often elicit apparently unconnected information that later proves crucial. Seeking corroboration helps in this process: by asking the same question of many different people, investigators assess reliability and perhaps motives of witnesses. For example, knocking on enough doors and asking, How many people live here? and How many people live next door? can unmask incriminating lies. 3. How might the questions How many people live here? and How many people live next door? unmask incriminating lies? Everyone is a Suspect The search for a suspect is comprehensive and impartial. It even includes the person reporting the crime, since murderers often turn out to be the very people who find the body. Nobody is ruled out, however disturbing the implications, and however much their accusation might conflict with popular preconceptions. The abduction and murder of children provides and instructive, if harrowing, example of this principle. Stranger danger attracts intense media interest- but only because such cases are rare. In the overwhelming majority of crimes, the perpetrator is known to the victim. This knowledge led investigators to doubt Lindy Chamberlain s claim that a dingo (wild Australian dog) had taken her baby, but this notorious Australian case also neatly illustrates the risk of preconceived ideas. Azaria Chamberlain was just two months old when she disappeared from a tent during a family holiday in Ayers Rock, Australia. The girl s parents long maintained that a dingo took the child from the tent, even as they were sentenced to life in prison for the murder of their daughter. Years later the cause of death of baby Chamberlain was proven to be a result of being attacked by a dingo. Investigators who jump to conclusions are more inclined to overlook evidence that conflicts with their initial views. The longer an assumption guides an investigation, the more difficult it is to set it aside and consider alternatives. In the Dingo Baby case, failure to do this led to a miscarriage of justice. 4. Why do you think investigators concluded that the Chamberlain s murdered their child?

3 Diligent detectives learn to question even apparently reliable evidence. For example, it is tempting to regard a suspect s confession as cast-iron proof of guilt, yet someone may confess to a crime they did not commit to protect the real perpetrator, or to hide a greater crime. Further probing, as well as corroborating evidence, is essential to prove that the person confessing is actually the culprit. 5. Why might investigators question reliable evidence and/or witness testimony? FIRST ON THE SCENE With sirens wailing, the emergency services rush to the crime scene. The police officers, along with fire and ambulance crews, see what the other investigators never will: a completely undisturbed site. But, before they can exploit this one chance to preserve and record evidence, they may have other, more urgent responsibilities. Whatever the type of crime scene, the priority is always to preserve life and assist any victims, ensuring that they are not in any danger. But once any injuries they have sustained are stabilized, and they are safe and composed, the importance of further assisting victims must be weighed against the risk that in doing so, evidence may be destroyed. For example, the victim of an assault is not allowed to be cleaned or bathed, in case they have the suspect s blood, skin, or hair on their hands. 6. What is more urgent than preserving and protecting the crime scene? After supporting the victims, the next-and obvious-role of the police is to detain and remove suspects. The apprehended are searched and their condition, statements, and behavior are all documented. Items of clothing may also be seized for forensic analysis. A less obvious police task is to make sure that suspects cannot return to the crime scene. Their return may make it difficult to prove at trial that traces of their presence, such as footprints, fibers, or hairs, originated when they committed the crime, rather than when they returned to the scene under police supervision. 7. Why should suspects be removed from the scene and NOT allowed back?

4 Part of the job of those first on the scene is to detain both willing and reluctant witnesses; people who see a crime committed are not necessarily eager to relive the experience in pursuit of justice. Even if they are not eyewitnesses, people near the scene can nevertheless provide information that might prove valuable in the investigation. If it is impossible to take statements from them immediately, witnesses should be separated to prevent them from discussing what they saw. 8. Why do you think it is necessary to keep witnesses separated? Secure the scene The more people that visit a crime scene, the more difficult it is for investigators to reconstruct what happened, and to identify potential suspects. So the next priority is to seal off the crime scene and protect any evidence it contains. Sealing off a crime scene is not just about enclosing it in a ring of tape. An effective plan for controlling the scene must also define a single route in and out. Personnel numbers should be kept to a minimum, and all visitors should wear protective coveralls to avoid cross-contamination. It is also important to document every visitor to the scene. An accurate log of when each arrived and left and what they removed can be used at trial to deflect defense accusations of evidence tampering. 9. What is an example of cross-contamination at a crime scene? Examination of the crime scene Foresight and a methodical approach by those first on the scene can help preserve and record evidence that might otherwise be destroyed. Unthinking routines such as flushing toilets or using the telephone can dispose of vital evidence, and recording whether a door was open or closed can make the difference between a killer being jailed or walking free. When crime scene managers reach the scene, their primary aim is to interview the police officers who arrive initially, in order to document the crime scene. By walking through the area together, investigators can collect information about transient evidence, such as dissipated odors. So those first on the scene need to register as much information as possible about the undisturbed surroundings. Further forensic investigation could hinge upon what they report. 10. Based on what you read in this paragraph, what is the meaning of the word transient?

5 Review A sixteen year old female describes the suspect of a hit and run as an old guy, around 50 driving a motorcycle 11. Who should be INCLUDED in the suspect pool based on the girl s response? a. all males over 50 with motorcycle license b. males 50 and below with motorcycle license c. men and women over 50 with motorcycle license d. men between with motorcycle license 12. Which of the following is NOT a responsibility of the first responding officer? a. save and preserve life b. determine the cause of death c. protect the scene d. a, b and c An officer is sent to an apartment located ½ mile away from a crime scene to apprehend a suspect. The officer escorts the suspect to the crime scene so he can observe and record the suspect s reaction to seeing the dead victim in a pool of blood on the bed. The suspect is then brought to the police department for further questioning. 13. What is the incorrect procedure in the scenario above? A crime scene consists of three locations: the victim s car in a parking garage, an abandoned building where the victim was found and the victim s apartment where pools of blood were found. An officer arrives at the abandoned building where he logs in with the crime scene manager and visually inspects the scene. The crime scene manager sends the officer to the victim s apartment and car to search for the victim s cell phone. 14. What is the incorrect procedure in the scenario above? 15. The first responding officer notices footprints in the freshly fallen snow as he approaches the crime scene in barn. In what sequence should the officer proceed considering the temperature is rising rapidly and the footprints will most likely melt within 3o minutes. a. take photos of the foootprints then enter the barn to check for victims b. check on the safety of victims then take photos of the footprints c. put up caution tape around the footprints then enter the barn to check for victims d. call for back up then take the photos of the footprints

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