Study Notes on Death Investigation in Criminalistics

Chapter 5: Death Investigation

Scene Investigation

  • A critical phase of the death investigation involves a preliminary reconstruction of events leading up to death.
    • All significant details of the scene must be recorded in order to form an accurate narrative of what transpired prior to death.
Documentation

  • Blood Spatter and Flow Patterns:

    • Must be meticulously documented as they can provide information regarding the position of the victim and the nature of the altercation.

  • Tire Marks and Shoe Prints:

    • Any tire marks or shoe prints present must also be documented to establish identifiers related to vehicles or individuals involved.

  • Fingerprints:

    • Collect and process any fingerprints from the scene to potentially link suspects or victims to the crime.
Collection of Evidence

  • Discarded Items:

    • Collect any evidence discarded, dropped, or left behind by a perpetrator as it may provide crucial leads.

  • Weapons:

    • Weapons, fired bullets, and casings must be collected and thoroughly documented.

  • Photographic Evidence:

    • Photographs of the scene must always be taken before any alterations or changes are made to the scene to ensure an accurate visual record.

The Autopsy

  • Definition:

    • An autopsy, broadly defined, is the examination of a body after death, formally referred to as a postmortem examination.

  • Goals:

    • A forensic/medicolegal autopsy aims to determine the cause and manner of death, which may be crucial for legal proceedings.
Evidence from the Autopsy

  • Examination Process:

    • The medical examiner or coroner conducts a careful examination of the victim to establish the cause and manner of death.
    • Tissues and organs might be retained for further pathological and toxicological examinations.
    • Proper arrangement between the examiner and the investigator is essential to secure various items obtainable from the body for laboratory analysis.

  • Items Collected:

    • Victim’s clothing
    • Fingernail scrapings
    • Combings from head and pubic hairs
    • Buccal swab for DNA typing
    • Swabs (vaginal, anal, oral) in the case of sex-related crimes
    • Recovered bullets from the body
    • Hand swabs from shooting victims for gunshot residue analysis
    • Swabs from areas suspected of DNA contact (touching or saliva)
    • Additional hand swabs or swabs for gunshot residue analysis.

External Examination

  • The forensic autopsy encompasses both an external examination and an internal examination.
External Examination Details

  • Overview:

    • Provides a broad overview of the state of the body and the clothing it was wearing at the time of death.

  • Injury Classification:

    • Classifying injuries involves distinguishing between types of wounds, such as stab wounds versus gunshot wounds.

Internal Examination

  • The internal examination usually involves the following procedures:
    • Incision Technique:
    • A Y-shaped incision is made starting from the top of each shoulder and extending down to the pubic bone.
    • Organ Dissection:
    • Each organ is weighed, dissected, and sectioned to assess their condition and relevance to the cause of death.

Toxicology

  • During the internal examination, toxicological specimens are taken, including samples of:

    • Blood
    • Stomach contents
    • Bile
    • Urine

  • Testing Protocols:

    • Blood is routinely tested for the presence and levels of alcohol and drugs.
    • Some drugs may redistribute or reenter the bloodstream postmortem, complicating interpretations of postmortem blood levels.

Cause of Death

  • Objective of Autopsy:

    • One primary goal of the autopsy is to determine the cause of death.

  • Common Causes of Death Include:

    • Blunt-force Injury:
    • Caused by a non-sharpened object (e.g., bat, pipe).
    • Can lead to abrasions, lacerations, or contusions due to ruptured blood vessels beneath the skin.
    • Sharp-force Injury:
    • Results from weapons with sharp edges (e.g., knives).
    • Important to check for defensive wounds during examination.
    • Asphyxia:
    • Involves conditions that interfere with oxygen intake (e.g., hanging, strangulation, carbon monoxide poisoning from fire).
    • Gunshot Wound:
    • Results from projectiles fired by a firearm.
    • Distance from the target plays a significant role in characterizing gunshot wounds.
    • Substance Abuse:
    • Commonly observed in forensic cases and may contribute directly to death or result in complications leading to death.

Manner of Death

  • Definition:

    • The manner of death refers to the circumstances leading to the fatal outcome.

  • Death Certification Classifications:

    • Homicide:
    • Non-accidental death due to gross negligence, reckless actions, or intentional acts by another person.
    • Suicide:
    • Self-inflicted death.
    • Accidental:
    • No intent to cause harm, often stemming from gross negligence.
    • Natural:
    • Death due to disease, environmental impacts, or age.
    • Undetermined:
    • Situations where classification cannot be rationally established.

Estimating Time of Death

  • Reminder:
    • Pathologists cannot determine an exact time of death, but various methods can approximate it.
Methods for Estimation

  • Algor Mortis:

    • The process by which a body cools to match the environmental temperature, losing heat generally at a rate of 1-1.5°F per hour until environmental temperature is reached.
    • Influenced by factors like body size and clothing.

  • Livor Mortis:

    • Blood settles in lower body areas post-death, starting 20 minutes to three hours after death and persisting for up to 16 hours.
    • Patterns of lividity may indicate whether a body has been moved post-death.

  • Rigor Mortis:

    • The stiffening of muscle tissues and body parts, typically occurring within the first 24 hours and dissipating within 36 hours.

  • Other Indicators:

    • Testing potassium levels in the vitreous humor can aid in estimating time of death.
    • Stomach contents can indicate the deceased's last meal and the extent of digestion assists in timing death.
    • Decomposition eventually occurs, rendering previous time of death estimates ineffective.

Recovering and Processing Remains

  • Sites where human remains are found are to be secured as crime scenes.
    • Comprehensive searches are imperative to locate all skeletal remains, evidence, and items such as footwear impressions.
    • Documentation and collection of evidence must be thorough.

Forensic Anthropology

  • Definition:
    • Forensic anthropology focuses on identifying and examining human skeletal remains.
Analysis of Bones

  • Demographic Information:

    • Examination can reveal information about the individual, including sex, approximate age, race, and skeletal injuries.
    • Sex determination relies on size and shape of skeletal features (especially the pelvis and skull).
    • Racial ancestry can be inferred from specific cranial features.

  • Estimating Height and Age:

    • Height can be estimated by measuring long bones.
    • Changes in bone structure, fusion, and dental development inform age assessments.
    • Anthropologists may also create facial reconstructions from skeletal remains.

Forensic Entomology

  • Definition:
    • The study of insects in relation to criminal investigations and is often used to estimate the time of death.
Estimating Time of Death Using Insects

  • Developmental Stages:

    • By assessing the most developed stages of flies found on a body, entomologists can approximate the postmortem interval (PMI).
    • The sequence of insect arrivals can also assist in estimating PMI.

  • Common Species:

    • The blowfly, typically recognized by its green or blue coloring, is commonly observed in forensic cases.

  • Lifecycle Analysis:

    • Blowflies lay eggs on remains, which hatch into maggots that consume human tissues and organs.
    • Examining developmental stages of fly larvae helps in estimating the duration since the body has been exposed.

  • Considerations for Accuracy:

    • Estimations of time required for insect development can be influenced by environmental conditions (geographical location, climate, weather).
    • Forensic entomology experts should collect all entomological evidence, including temperature readings and samples from all locations of discovery.