forensic necropsy - vvma.org vvc/speaker proceedings... · •mechanism of death 2 ... •a...

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The Forensic Necropsy and Report: An Introduction to Veterinary Forensic Pathology

R h l T DVM

© 2012 ASPCA®. All Rights Reserved.

Rachel Touroo, DVM

Director of Veterinary Forensic Sciences

American Society for Prevention of Cruelty to Animals

Learning Objectives•Familiarity with veterinary forensic pathology•Understanding of the purpose of a forensic necropsy•Understanding of the following terms:

•Cause of death•Manner of death•Contributory causes of death•Mechanism of death

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•Mechanism of death•Postmortem interval

•Familiarity with the approach and components of a forensic necropsy

•Understanding of how to appropriately document and photograph a forensic necropsy

• Familiarity with evidence preservation, identification, collection, storage and chain of custody related to a forensic necropsy

•Familiarity with the components of a forensic necropsy report

Overview

1. The differences between a forensic necropsy and a traditional necropsy

2. Postmortem changes

3. Forensic necropsy-external exam

4. Forensic necropsy-internal exam

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5. Forensic necropsy report

Forensic Necropsy •The forensic necropsy starts at the scene

•Many findings can not be correctly interpreted without information regarding the history, crime scene findings and information on how the body was handled, transported, and stored

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Forensic Necropsy•Necropsy findings, along with the crime scene findings are used to determine the cause and manner of death

•Some causes of death, such as drowning or other asphyxialdeaths, are best supported by crime scene findings and witness statements rather than by necropsy findings

• Ideally the veterinarian should be present on scene

If they are unable to be present on scene all pertinent

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• If they are unable to be present on scene all pertinent information regarding the case should be provided

Forensic Necropsy• The investigating agency should provide the veterinarian with all pertinent information regarding the case such as:

• History

• All circumstances leading up to and surrounding the animals death

• Including but not limited to:

• Date and time the animal was last seen alive

• Date and time the animal was found to be deceased

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• Any available medical history

• Crime scene information such as:

• Location of the body

• Temperature and other conditions the body was exposed to when discovered

• Access to food, water, shelter

• Diarrhea , vomitus or blood present

• Information on how the body was handled, transported, and stored prior to you receiving it

• Refrigerated, frozen, or neither

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Forensic Necropsy

•The specific goals for a necropsy should be discussed with the investigating agency

•The veterinarian needs to have a clear understanding of what information the investigating agency is hoping to

bt i f th thi id th i

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obtain from the necropsy, as this may guide them in determining what diagnostic and forensic testing should be completed

•Additionally, the investigating entity should be aware of any limitations regarding the information they are seeking

Forensic Necropsy

•The role of a traditional necropsy is to identify, characterize and record lesions in order to:

•Determine cause of death

•Confirm or deny clinical assumptions and diagnoses

•Chronicle disease progression

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•Provide feedback on implemented therapies

•A forensic necropsy however, is preformed in order to investigate unnatural and suspicious, possible litigious or criminal deaths

Forensic Necropsy

•Multidisciplinary approach:

•Law enforcement

•Toxicology

•Entomology

•Anthropology

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p gy

•Pathology

•Botany

•Ballistics

•Odontology

•DNA analyst

•Other forensic

analysts

Forensic Necropsy

•The goals of a forensic necropsy:

•Determine:

1. Cause of death

2. Manner of death

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3. Contributory causes of death

4. Mechanism of death

5. Estimate the postmortem interval

Forensic Necropsy

•Cause of death

•The injury, disease, or combination of the two that initiatesa train of physiological disturbances that, no matter how brief or prolonged, results in the fatal termination of an animals life

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Forensic Necropsy

•Manner of death

•Explains how the cause of death came about, and can be listed as either:

•Natural•Accidental

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•Non-accidental or unlawful•Euthanasia•Undetermined

•The cause and manner of death are opinions based on the total case investigation with careful synthesis and analysis of all the available information

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Forensic Necropsy

•Contributory causes of death

•Diseases or injuries that significantly contributed to the cause of death

•One or more contributory causes may be present

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•Mechanism of death

•The physiological derangement resulting in death

Forensic Necropsy

•Postmortem interval estimation

•The postmortem interval (PMI) refers to the time since death or the time that has elapsed between the death of the animal and the attempt to determine the time of death

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Forensic Necropsy

•A necropsy should be preformed as soon as rational

•Bodies should not be frozen

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Forensic Necropsy

•The following steps should be taken on scene in order to preserve any evidence present on a deceased victim:

•Utilize proper PPE as needed to prevent contamination

•Prevent cross contamination by utilizing sterile procedures

•Handle and/or move the body as little as possible

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•Place paper bags on all four feet on scene and secure them in place with rubber bands

•Wrap the body in a clean sheet prior to placing it in a body bag

Forensic Necropsy

•Receiving the body

•The original evidence receipt or log should accompany the animal in order to maintain chain of custody

•Note the date and time that you take custody of the body on the original evidence receipt

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Forensic Necropsy

•Document how the body was received

•Describe how the body was packaged and stored prior to necropsy

•Photos should be taken of the packaging the animal was received in

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•Remember the animal is evidence

•Photos need to be taken before anything is altered

•Photos need to be taken as each piece is unwrapped

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LabelLabel

Label

Sample Photos: Document How the Body was Received

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Sample Photos: Document How the Body was Received

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Postmortem Changes

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Postmortem Changes

•Following death many physicochemical changes occur ultimately leading to the dissolution of all soft tissues

•Must be familiar with these postmortem changes so that they are not misdiagnosed as antemortem lesion

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•The medicolegal importance of these postmortem changes is related to their sequential nature which may be utilized in the estimation of the time of death

Postmortem Changes

•Stages of death:

•Cessation of breathing

•Cardiac arrest

•Pallor mortis

•Algor mortis

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g

•Livor mortis

•Rigor mortis

•Decomposition

•Autolysis

•Putrefacation

•Skeletonization, mummification or saponification

Postmortem Changes•Algor mortis

•Postmortem cooling of the body

•Body will cool from internal temperature to the ambient temperature

•Affected by numerous variables

•Size, hair coat, ambient temperature, etc

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Size, hair coat, ambient temperature, etc

•Animals temperature at time of death is unknown

• In humans, under average conditions, the body temperature drops at an average of 2-2.5°F per hour during the first hours and then slows to an average loss of 1.5-2°F during the first 12 hours and 1°F for the next 12-18 hours (Spitz and Fisher, 1993)

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Postmortem Changes

•Algor mortis

•There is an initial maintenance of body temperature which may last for some hours, which is referred to as the “temperature plateau.” This is followed by a relatively linear rate of

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cooling which slows rapidly as the body approaches the environmental temperature.

•This temperature plateau generally lasts half and hour to one hour but can last as long as 3 hours in humans

•Actual length of the postmortem temperature plateau is unknown

Postmortem Changes

•Livor mortis (lividity)

•Postmortem “discoloration” of the body due to pooling of the blood in dependent sites of the body, except the areas exposed to direct pressure

•Visible in light colored skin, buccal mucosa, sclera, and i t l f A ddi h l t l

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internal surfaces. Appears as a reddish purple to purple coloration.

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Photo courtesy of Jason Byrd

Livor on buccal aspect of lip in a dog

Postmortem Changes

•Lividity is able to develop postmortem under the influences of gravity because the blood remains liquid rather than coagulating

•Within 30 to 60 minutes postmortem blood becomes incoagulable

Thi i d t th l f fib i l i

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•This is due to the release of fibrinolysins

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Lividity observed on internal surfaces (left lung lobes). Note lack of lividitywhere the lung lobes were pressed up against the ribs (arrows).

Postmortem Changes

•Lividity maybe misinterpreted as bruising

•Can be differentiated by incising the area. Bruising has diffuse hemorrhage into soft tissues, whereas with lividity blood is

fi d t th l

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confined to the vessels.

•However, can be difficult to differentiate with advanced decomposition as the vessels become permeable

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Postmortem Changes• In humans, lividity usually becomes apparent within 30 min to 2 hrs postmortem and becomes more prominent over time

•Livor can “shift” until it is said to be “fixed”

• In humans, lividity typically becomes “fixed” within 8-12 hrs postmortem

•Livor is fixed when the blood leaked into the surrounding soft tissues due to hemolysis and breakdown of the vessels

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tissues due to hemolysis and breakdown of the vessels

•Fixation depends on the rate of decomposition

•Prior to fixation if the body is moved the blood will drain to the newly dependent area or if pressure is applied to an area of livorthe area where the pressure is applied will blanch

•Can assist in determining the position of the body at the time of death and if the body has been moved

Postmortem Changes

•Rigor mortis

•“Stiffening” of the body after death due to postmortem depletion of ATP

•In the absence of ATP the Myosin molecule heads become permanently bonded to the Actin molecule

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•This bond remains until decomposition destroys the Myosin and Actin bond

Postmortem Changes

•Rigor mortis•Initially the muscles are flaccid immediately following death, which is followed by rigidity with the depletion of ATP. The rigidity then gradually subsides and the body becomes flaccid again as it decomposes.

•Rigor mortis develops and disappears at a similar rate in

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g p ppall muscles. However, because of a lesser volume, small muscles become rigid before the larger muscles.•Therefore, you typically observe rigor mortis first in the face

•Once rigor is fully established the breaking of rigor mortis in joints is irreversible, however, if rigor is broken before it is totally complete, a variable extent of rigidity will reappear

Postmortem Changes

•Rigor mortis•May be able to assist in the determination of the postmortem interval•However, rigor is substantially modified by a variety of factors making the interpretation unreliable

•If there is a decrease in ATP antemortem rigor mortis will

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If there is a decrease in ATP antemortem rigor mortis will set in more quickly•Causes of decreased ATP antemortem include: extreme physical activity, severe convulsions, and hyperthermia •Therefore, heat can accelerate the process

•Conversely, cold delays the onset of rigor and prolongs its presence

•Rigor mortis may be delayed or weak in emaciated individuals

Postmortem Changes

•Rigor mortis

• In rare instances the onset of rigor can be almost immediate

•Referred to as “cadaveric spasm”

•Usually occurs in deaths preceded by great excitement or tension

• In humans rigor may:

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• In humans, rigor may:

•Appear in 2-4 hrs

•Reach full formation in 6-12 hrs

•Disappear in 36 hrs to 6 days

•All depends on perimortem factors, cause of death, and temperature conditions

• In hotter conditions, rigor can come and go in 24 hrs or less

(DiMaio and DiMaio, 2001)

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Rigor mortis in a dog. What is wrong with this photo?

Photo courtesy of Jason Byrd

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Postmortem Changes

•Rigor mortis

•The degree (complete, partial or absent) and the distribution of rigor should be assessed during necropsy after establishing that no artifact has been introduced by previous manipulation of the body

Wh th f i id li b i i i t t ith

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•When the appearance of rigid limbs is inconsistent with gravity, rigor is a reliable indicator of a postmortem change in the position of the body

The Forensic Necropsy

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The Forensic Necropsy

Forensic Necropsy

•There are 3 basic steps for any necropsy:

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Observe Describe Interpret

Forensic Necropsy- External Exam

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•Full body radiographs (at least 2 views) should always be obtained prior to a forensic necropsy

•Provides valuable information regarding a history of abuse

•May observe recent, healing, or healed fractures

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•Most victims of abuse have been subject to repetitive abuse

•Done in order to locate and document internal evidence of injury

•Especially important with penetrating injuries and with animals that have been shot

Forensic Necropsy- External Exam•Photography

•First photo of a series should be of a photo board

•The photo board should include the case number (internal and investigating agencies number if

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investigating agencies number if applicable), location, date, and animal ID number

•The second photo of the series should be of the animal and contain the photo board

•Subsequent photos do not need to contain the photo board

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Forensic Necropsy-External Exam

•Photography

•Overalls to identify the animal

•Photographs of the entire body

•Right lateral, left lateral, cranial, caudal, dorsal, and ventral

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•Orientation

•Reference photo used to identify the location of any lesion or item of interest

•Close-ups

•Detailed photograph of any lesion or item of interest

•With and without a forensic ruler/scale

Sample Overall Photos

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Sample Orientation and Close-up Photos

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•External exam is an important part of a forensic necropsy and is often overlooked

•Similar to a forensic medical exam on a live patient (with some exceptions)

•Systematic approach

N t ll l d b l fi di

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•Note all normal and abnormal findings

•Evaluate ALL body systems

•Do not forget the eyes, ears, mouth, feet, nails, tail, and perineum

•Any lesions should be described and located on a diagram as well as the location described by anatomical landmarks and photographed

Sample Necropsy Diagram

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Skin (Wounds and Scars), Hair coat

Veterinarian: __________________________ Date: ________________________

Law Enforcement Agency:________________ Case #:_______________________

Dog ID #: ______________ Distinguishing Marks/Comments: ________________

___________________________________________________________________

Recent wounds – Red marks

Scars ‐ Blue marks

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Note: Ears removed from lateral views so that

wounds/scars under ears can be diagrammed.

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The Bergh Memorial Label Animal Hospital of the ASPCA

424 E 92nd Street, New York, N.Y. 10128(212) 876-7700

Hair coat and Nails - Long Haired: Dog Cat

Choose 1, 2, 3 or 4 to describe matting

1. Haircoat a single mat that prevents normal movement and interferes with vision. A complete clipdown required. Yes No

2. Substantial matting of haircoat. Large sections of hair matted together. A complete clipdown required. Yes No

3. Numerous mats, but animal can still be groomed without a total clip down. Yes No

4. Hair coat is dirty and/or has a few mats. Yes No

Foreign material embedded in mats. Yes No

Visible feces on coat Yes No

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Visible feces on coat Yes No

Fecal / urine staining of hair coat; Yes Noof legs Yes Noof ventrum Yes Noof hind end Yes Noother ______________________ Yes No

Strong offensive odor from coat. Will require one or more baths to resolve odor. Yes No

Pododermatitis. Yes No

Choose 1 or 2 to describe toe nails

1. Nails extremely overgrown Yes No

2. Nails long Yes NoNails penetrate pads (Describe; inflammation, pain?)

Nails interfering with normal gait. Yes NoCopyright © 2001 The American Society for the Prevention of Cruelty to Animals, Inc. A ll Rights Reserved.

Reprinted with the permission of ASPCA, 424 E. 92nd St., New York, NY 10128 (212) 876-7700.

Forensic Necropsy- External Exam• Be sure to document the following:

• Date and time of the necropsy• Indicate the time the necropsy began and when it is completed

• Postmortem condition• Good, fair, or poor

• Postmortem changes• Insects activity on the body• Signalment

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g• Species, breed, sex, age• Also note other descriptors and distinguishing characteristics such as coat pattern and color, special markings, tattoos, microchip, etc

• Animal identification information• All animals should be given a unique individual number

• BCS• Purina has a useful BCS scales available for dogs and cats

• Weight• Body and individual organs

• Length and height

Forensic Necropsy- External Exam•Document and describe any item(s) on or accompanying the body

•Collars, tags, blanket, etc.

•Document and describe any evidence of medical intervention

•IV catheters shaved areas bandages sutures etc

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•IV catheters, shaved areas, bandages, sutures, etc.

Forensic Necropsy- External Exam•External Exam

•Don’t forget physical evidence!•Physical evidence is any tangible objects that can establish that a crime has been committed, or can provide a link between a crime and its victim or a crime and a suspect.

•Depending on the case you may want to collect items such as:

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•Biological evidence•Firearm evidence •Toxicological evidence•Entomological evidence• Impression evidence•Trace evidence

•May need to utilize an alternative light source to help identify physical evidence on the body


•Collection of evidence

•Evidence should be photographed in place before being altered

•Exact location of the evidence should be noted (measured in and sketched on a diagram)

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•Measure from a fixed anatomical point

•For example, the items is 3cm caudal to the lateral canthus of the right eye

•Item should be measured and described

•When applicable utilize 3-D measurements

Forensic Necropsy- External Exam•Collection of evidence

• Item should be properly handled

•Prevent contamination by wearing gloves, masks, gowns, and caps as appropriate

•Prevent cross contamination by utilizing sterile procedures to collect items of evidence

Fi i f id h ld l b h dl d i h l i

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•Fine pieces of evidence should also be handled with plastic tweezers in order to prevent damage to the item during removal

•Bullets or bullet fragments should never be handled with metal instruments!

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Forensic Necropsy- External Exam•Evidence must be properly stored

•Paper evidence bags or envelopes should be used instead of plastic bags in many instances as many items will mold if stored in a plastic bag due to the build up of moisture, which will damage the evidence many times rendering it useless

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rendering it useless

•If evidence is wet it should be allowed to dry before being packaged in a paper evidence bag

•Accelerants should be placed in a special container for arson evidence or an uncoated paint can

•Accelerants are volatile substances and may escape if not properly stored


•An item of evidence must always be accompanied by its original chain of custody form

•Any physical evidence that is collected from a body, such as a buccal swab, needs to have an evidence receipt

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•Should also maintain a log of items of evidence that our in or have been in your custody

Forensic Necropsy- Internal Exam

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Forensic Necropsy Internal Exam

Forensic Necropsy-Internal Exam•Basic necropsy tools

•Knives•Boning knife and skinning knife

•Scalpels•Sharpening tools

•Sharp knives are essential•Rib cutters

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Rib cutters•Garden shears or loppers

•Saw•Stryker saw

•Skull key•Digital scale (for organs)•Whirl-pak bags•Scissors, hemostat, forceps (metal and plastic)•Specimen jars (various sizes, glass and plastic)


•Basic necropsy tools cont.•Evidence packaging materials•Probe (with scale)•Camera, forensic ruler, and ID board or card•Scale P h bi

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•Punch biopsy•Syringes•Otoscope•Ophthalmoscope•Specimen cassettes•10% buffered neutral formalin•Clippers


•Basic steps of the internal exam

•Skinning

•Opening the body

•Removal of organs

•Examination of organs

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g

•Sampling of organs

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•Photography

•Photographs should be taken of the following during the internal examination:

•Overalls of the body after the skin has been completely removed

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•Overalls of the body after the thorax and abdomen have been opened

•Orientation and close-ups of all lesions with and without a forensic ruler


•Document all normal and abnormal findings

•It is crucial to fully describe all lesions

•Including:

•Location

•Distribution

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•Color

•Size

•Measurements should be three dimensional when possible

•Measure volume of effusions using syringes


•Describing lesions cont:

•Shape/margins

•Consistency and texture

•Surface appearance

•Number and extent

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•Content (when applicable)

•Odor (when applicable)


•Morphologic diagnosis

•A short phrase which summarizes a gross or microscopic lesion or tissue change

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•Internal examination

•There is no one “correct” way to perform a necropsy but the necropsy must be through

•Following the external exam the internal exam is begun by reflecting the front and hind legs dorsally

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•Internal examination•After the legs are reflected the body should be completely skinned allowing for examination of

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gthe subcutis for evidence of hemorrhage, bruising, and wounds that were not obvious during the external exam

•Any wounds should be located on a diagram as well as the location described by anatomical landmarks

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•After the carcass has been skinned the abdomen can be opened

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•Internal examination•The next step is to open the thorax

•Then incise the diaphragm along the thoracic wall

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along the thoracic wall

•Next incise the tissues over the sternum to allow for the ribs to be removed with loppers or shears

•Once the ribs are removed the thoracic wall and ribs should be carefully evaluated looking for any rib fractures or wounds



•Next the organs can be removed

•First remove the pluck which consists of the tongue, esophagus, trachea, thyroid, lungs and heart

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• Internal examination

•Following removal the pluck should be examined

•The entire length of the trachea and esophagus should be opened

•The lungs should be incised and palpated

•All sections of the lungs should readily float in formalin

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g y

•The heart should be opened and valves examined

• If there is a suspicion of cardiac disease measurements and weights should be obtained


•Internal examination cont.•Next the abdominal organs can be removed

• Spleen in easily removed• Check the gallbladder for patency

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before removing the liver• Then remove the stomach, small intestines, cecum, and large intestines• If the rectum and anus need to be removed the pelvis will need to be split

• The adrenal glands should be removed before the kidneys

• Be sure to obtain a urine sample before fully incising the bladder


•Internal examination•Following removal the abdominal organs they should be examined•The liver and spleen should be

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pincised

•The kidneys should be sectioned from cranial to caudal pole and the capsule removed, checking for any adhesions

•The adrenal glands should be incised

•The bladder should be opened and the mucosal surface examined

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•Internal examination•Next the joints should be examined and a sample of the bone marrow obtained from a long bone

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•Lastly, the brain is removed and examined•First the head is removed at the atlantooccipital joint

•Then remove the temporalis muscle bilaterally to expose the skull

•Make the cuts indicated on the next slide to remove the brain from the skull

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•Internal Exam•Don’t forget physical evidence!•Depending on the case you may want to collect items such as:•Biological evidence

•For example: feces free fluid bone marrow tissue

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•For example: feces, free fluid, bone marrow, tissue samples, etc

•Firearms•Bullet or portions of

•Toxicology•Blood, urine, gastric contents, vitreous humor, liver, bile, etc.

•Virology or bacteriology


•Internal examination•Saving samples

•Samples of all organs and lesions should be saved in 10% neutral buffered formalin for histopathology. All sections should at most be 1cm thick.•Formalin will only penetrate 1cm in 24 hrs

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Formalin will only penetrate 1cm in 24 hrs•The total amount of formalin present should be 10 times the amount of tissue present

•Depending on the case, you may want to consider collecting the necessary samples for microbiology, virology, parasitology, clinical pathology, and toxicology •When in doubt it is best to collect and hold a sample for testing at a later date if it is determined that it is needed

Sample Histology Checklist

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Sample Necropsy Worksheet

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The Forensic Necropsy Report

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The Forensic Necropsy Report

•The purpose of the forensic necropsy report is to clearly convey the decedents condition and an understanding of what has or has not occurred to the victim

•Must educate the investigators, prosecutors, the judge, and the jury

•The veterinarian must ensure that the court understands what has

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happened to the victim

•But must be aware of their limitations and the gaps in veterinary forensic knowledge

•There is no ‘standard’ format

•Your final report is not just your gross necropsy findings

Forensic Necropsy Report

•The necessary components of a forensic necropsy report:•Introduction

•Should include the following:•Investigating agency, lead officer, this agencies case number and animal identification number

•Purpose of the necropsy

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•Purpose of the necropsy•Date, time, and location of the necropsy•Those in attendance

•Crime Scene Findings•Personal observations or information provided

•History•A medical history for the animal may or may not be available

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Forensic Necropsy Report•The necessary components of a forensic necropsy report cont:

•Gross description of findings•Presentation of the body•Postmortem changes•External exam findings• Internal exam findings

•Gross diagnosis•Ancillary procedures, laboratory tests and results

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Ancillary procedures, laboratory tests and results•List and explain

•Cause of death• Including manner of death, any contributory causes of death, mechanism of death, and estimated postmortem interval as applicable

•Comments/Conclusions• Interpretation of findings and summarizes the events leading up to and causing the animals death (when possible)•Address duration and degree of pain and suffering•Note if death is an approved method of humane euthanasia (AVMA guidelines on euthanasia)

Forensic Necropsy Report

•Additionally, I find it beneficial to summarize findings in conjunction with photos in order to enhance understanding and further illustrate the magnitude of the condition

•Pictures speak loader than words!

•Can utilize PowerPoint or Photoshop to integrate photos i t fi l t

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into your final report

•Can be utilized in court

Summary• Veterinary forensic pathology

• Branch of veterinary medicine concerned with determining the cause and manner of death

• The purpose of a forensic necropsy is to identify, document, and preserve everything of an evidentiary nature and anticipate questions that will be asked in the future

• The goals of a forensic necropsy are to determine:• Cause of death

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Cause of death• Manner of death• Contributory causes of death• Mechanism of death• Postmortem interval

• A forensic necropsy starts at the scene• Be meticulous and take your time

• There are no do-overs• Remember that the purpose of the forensic necropsy report is to clearly convey the victim’s condition and an understanding of what has or has not occurred to the victim

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forensic necropsy - vvma.org vvc/speaker proceedings... · •mechanism of death 2 ... •a...

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