Basic rules of crime scene investigation

Crime scene investigation

Things are not always what they seem to be at first sight. Many cases of homicide go undetected because of the lack of suspicion and improper or inadequate investigation. All cases of death should be regarded as unnatural, until proved otherwise. Violent deaths may show minimal or no external evidence of injury, and conversely natural deaths can occur under such circumstances as to suggest falsely that violence was used.

Accidental deaths and suicides can occur under circumstances which suggest homicide. One should observe in crime scene investigation, A person who appears to have died from acute alcoholic poisoning or from the combined effects of alcohol and other drugs, may have committed suicide by using drugs, or rarely he may have been poisoned criminally.

In a suicide case when observing crime scene investigation, alterations may be made at the scene because of disgrace. In a homicide case, the scene may be altered or rigged to suggest that death resulted from suicide or accident. Upset furniture, overturned lamps and other disturbances, and blood stains on walls and floors are consistent with a struggle between assailant and victim.

However, similar disturbance may be seen in case of suicide committed while the victim was acutely intoxicated by alcohol or some drug, or he was possesed by some form of psychotic excitement. In the crime scene investigation, The doctor must look for any possible inconsistencies between the apparent death scene and his actual scientific findings.

In a case of hanging, the manner in which a ligature is applied to the neck, or the mode of suspension of a body may determine the manner of death. In such cases, the real cause of death can be established by complete autopsy and police crime scene investigation. The investigating officer should obtain information about the circumstances of death and the background of the deceased.

The basic rules for crime scene investigation are

- Verify that a crime has been committed.

- Look for signs of how it was committed.

- Recover and preserve evidence that might lead to the arrest and conviction of the guilty.

The answers to the following questions (6W’s) have to be found to prove the guilt and convict the accused.

(1) Who is the victim? (identification).

(2) When the death and injuries occurred? (time of death and injuries).

(3) Where the death occurred? (scene and circumstances of death).

(4) What injuries are present? (description of injuries).

(5) Which injuries are significant? (major, minor, true, artifacts, postmortem injuries).

(6) Why and how injuries were produced? (mechanism and manner of death, i.e., natural, accidental, suicidal or homicidal). If unnatural, determine the means or agent causing death, e.g., knife, firearm, poison, etc., and if homicide assist in identifying the person responsible for death.

Duties of Doctor in crime scene investigation

Crime scene investigation aids in identification of suspects or victims, prove or disprove alibi, identify a modus operandi, establish the corpus delicti and establish associations among victim, suspect, scene and evidence. It is the responsibility of the police to preserve and protect the scene of crime.

The doctor should carry with him a hand lens, measuring tape and ruler, gloves, slides, swabs, chemical thermometer, and envelopes if possible. Complete and accurate recording of the scene as it was found is very important. This can be done by accurate diagrams, notes and photography. The scene may show evidence of a struggle, and on the body vital trace evidence may be present.

The examination at the crime scene investigation should be limited to a search for such evidence which might be dislodged or possibly lost during the transfer of the body to the mortuary. If a doctor sees the dead body for the first time in the autopsy room, he may form incorrect opinions about the origin of various injuries. Seeing the body at the scene of crime with the various surrounding objects, helps to avoid such mistakes.

The visit to the scene of death is more valuable if the body shows a patterned injury, the origin of which is in doubt. Even a retrospective visit to the scene enables the doctor to have a true appreciation of the nature of the surroundings, which are usually found to differ from the impression formed from the descriptions of other persons, and will be of help in interpretation of the findings in the victim.

The scene of a violent death usually shows significant findings for understanding, reconstructing and solving problems. The finding of a dead body together with evidence of burglary indicates murder. Disturbance of furniture may be seen sometimes, if a person dying suddenly and naturally falls down and injures himself.

The sequence of events preceding death must be reconstructed logically to support or contradict inferences from other areas of crime scene investigation. The fatal injuries should be evaluated to find out how much purposeful action and walking, the victim could have carried out before he became disabled and died.

In every case of crime scene investigation, priority must be given to the injured, and to any action designed to prevent further casualties. Evidence to connect victim, suspect and location of the murder may be found at the scene of the incident, on the clothing or bodies of victim and suspect, or some other place to which the body was transported.

(1) He must make sure that death has occurred.

(2) If the victim of an assault is living when first seen, the doctor must do everything to save the life.

(3) If death is about to occur, he should obtain a dying declaration, for otherwise valuable information will be lost, e.g., in criminal abortion.

(4) He must obtain all possible information regarding the crime.

(5) If he suspects foul play, the police should be informed.

(6) He should retain any material which is relevant, e.g. in cases of suspected poisoning, he must look for and retain any specimens, such as vomit, leftover poison, or drinking utensils.

(7) He must identify the body, which should also be identified by the relatives and the police.

(8) He must inquire whether the body has been moved at all before he first saw it.

(9) Never touch, change, or alter anything until identified, measured and photographed at crime scene investigation. He should ask the investigating officer before moving anything. Photograph the scene from several angles. He should follow but not lead the police around the scene.

(10) He should not give opinions without proper thought.

(11) In crime scene investigation, he should make adequate notes which should include:

  • (a) Date, time, address or location.
  • (b) Name and sex of deceased.
  • (c) A list of all persons present.
  • (d) General observation about the scene; any evidence of struggle, such as overturned furniture, disturbed wall hangings, broken door or window glass pieces, displaced articles or trampled ground. If outside, record the type of weather, the state of ground and the vegetation present.
  • (e) Temperature of the surroundings, and rectal temperature of the deceased should be taken.
  • (f) In crime scene investigation, doctor must Make a sketch noting such points of importance as direction and position of blood (pools or splashes) on the body and at the scene, position of the body and any weapons. If the weapon is in the hand of the deceased, note whether it is loosely held or tightly grasped. A correlation should be attempted between injuries present and possible weapons or other objects which might have caused them. The distribution of blood stains and their shape, which may point to the site of injury should be noted. Note the amount of bleeding at the scene. It makes the evaluation of injuries more accurate and may give indication as to the length of survival after the injuries. The plan need not be scale accurate, but the relative measurements should be accurate. Describe the clothing and note any tears, cuts, missing buttons, etc. Do not put objects through defects in clothing or wounds. Examine the hands and forearms for defense wounds. Make note of injuries and record them on body diagrams.
  • (g) Position and appearance of the body, rigor mortis, post-Mortem lividity, etc., which assist in estimating the time of death.
  • (h) Free hair, fibers or other foreign matter which is likely to be dislodged when the body is moved, should be searched and removed with adhesive tape.
  • (i) If there are any bite marks, they should be swabbed with a cotton wool swab moistened with saline. Saliva swabs may be taken after wearing gloves to prevent the soiling of the swab with sweat.
  • (j) The pubic hair should be combed in situ in cases of sexual assault, and loose hair collected.
  • (k) In cases of rape and suspected abortion, an absorbent pad should be strapped over the vulva to collect any fluid which may run out during the transfer of the body.
  • (l) The objects on premises, e.g., dates on mail and newspapers, condition of food on table, etc. to determine the time of death.
  • (m) Photograph any ligature before removal, cut if necessary leaving the knots intact.
  • (n) If a weapon is found, handle it with care to preserve fingerprints, blood stains, hair, fibers, etc.
  • (0) Leave firearms in the condition they are found. Note position of each bullet and casing.
  • (p) Bullets, etc., should be marked for identification.

(12) Use a pencil or other objects to open doors and cabinets. If the weapon is not found at the scene of death, advise the police about the type of weapon that is likely to have been used.

(13) He should not smoke or throw cigarette stubs, matches or anything at the place of suspected crime, as trace evidence including small items left behind by a suspect, may play a large part in the proof of the crime. Saliva on cigarette ends may be grouped to include or exclude suspects.

(14) The scene should be examined by fingerprint examiner, followed by a trace evidence specialist.

(15) Transfer the body to the mortuary wrapped in a large sheet of plastic or other clean cloth so as to retain any loose objects, hairs, fibers, etc.

(16) The police should be advised not to remove the clothing, etc. from the body.

Disadvantages of Doctor not visiting the Scene in crime scene investigation

(1) when the body is transferred to mortuary, fresh abrasions may be produced on it during transit.

(2) Clothing will be disarranged; blood stains will form on parts of clothes originally free from them. When the body is lying on the back with a stab wound on the front of the chest or abdomen, the external blood loss is minimal or absent. When the body is turned, large amount of blood may escape through the wound and stain the clothes.

(3) Fresh tears in clothes may be produced from rough handling.

(4) Existing rigor mortis may be broken down at least partially.