Brent E. Turvey
Winter, 1996

Title:
"
A GUIDE TO THE PHYSICAL ANALYSIS OF LIGATURE PATTERNS IN HOMICIDE INVESTIGATIONS"

Turvey, B., "A GUIDE TO THE PHYSICAL ANALYSIS OF LIGATURE PATTERNS IN HOMICIDE INVESTIGATIONS," Knowledge Solutions Library, Electronic Publication, URL: http://www.corpus-delicti.com/ligature.html, Winter, 1996

Note: Brent E. Turvey, MS is a full partner of Knowledge Solutions, LLC.
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The Role of the Investigator

The Homicide investigator's role in any given case is not to officially diagnose anything relating to the manner, mechanism, or cause of a victim's death. That is the is strict domain of the Medical Examiner or Coroner's Office. The Homicide investigator is interested in an accurate reconstruction of events that will lead them to a suspect. They are looking for presumptory tools that will make recognition, collection and any subsequent reconstructions of evidence a more competent reflection of the facts initially presented to them at a given crime scene. That is the general purpose of this work.

DEFINITIONS

The definition for ligature homicide in this work is concerned specifically with cases in which the victim has been garroted. This term applies to cases where an assailant has placed a ligature around a victim's neck and has tightened it for purposes of controlling, silencing, and/or killing the victim. Commonly documented examples of ligatures include, but are by no means limited to,: ropes, neckties, scarves, stockings, metal wires, shoe/boot-laces, necklaces, clotheslines, sweaters, brassieres, belts, and electrical cords. It is important to note that in cases of ligature homicide the mechanism of death is occlusion of the vessels supplying blood oxygen to the brain. The victim loses consciousness in between 10 and 15 seconds(DiMaio et al[4]).

The definition for cases of ligature homicide in this work does not include victims of homicidal hangings. Hanging cases can often be quickly distinguished because they are marked by a classic "V" shaped pattern on the victim's neck associated with the knot in the ligature. In cases involving a suspended hanging, the "V" will point away from gravity, and be much higher on the neck (Knight et al. [7]). In cases where the victim has been "hog tied" by an assailant, the "V" will point towards gravity(Carver [3]).


ASSUMPTION OF HOMICIDE

There is general agreement in the literature that cases involving strangulation by ligature are most commonly homicides (Adelson [1], [3], [4], Geberth [5], [7], Vanezis [9]). Furthermore, Knight et al. [7] suggests that all cases of ligature strangulation be investigated as homicides until the opposite can be demonstrated. That course will help to define the procedural scope and weight of an investigation early on.

When investigating any homicide case, it is very important that certain specific measures always be taken at the crime scene to insure the best possible results. The specific purpose of this work is to outline some procedural concepts regarding recognition, documentation, collection, identification, comparison, and individualization of homicidal ligature patterns. Following those brief sections, a discussion on the subsequent reconstruction of events from ligature patterns will conclude.


RECOGNITION OF LIGATURE PATTERNS

When ligature strangulation is suspected or alleged, begin the investigation with a surface examination of the victim's neck. It sounds simplistic, but there is a reason for specifically working from the body out to the rest of the crime scene in these cases. If the ligature is not immediately present (i.e. - around the victim's neck), the distinctive pattern of the ligature may tell investigators what kind of ligature to search for at the scene or at other connected scenes. Or if purported constricting devices could have caused the ligature pattern that the investigator is presented with.

In the absence of a ligature still around the victim's neck when the body is discovered, attempt to determine if there is indeed a visible ligature pattern present. A ligature pattern is generally going to be located about the level of the victim's larynx or lower. In homicide cases it is generally going to be a uniform and horizontal mark encircling the neck completely. But it can also be a partially circling mark, visible only in the front, the assailant having pulled the ligature tightly from behind. This is in keeping with a homicidal strangulation rather than suicidal or homicidal hanging[6]. In either case, the ligature pattern will mark the skin of the neck generally the same way all around, and will not rise sharply to a suspension point([7], [9]).


MISLEADING PATTERNS

What should be recognized as a ligature pattern or furrow on a victim's neck is sometimes best thought of in terms of what is not a ligature pattern. Beware to exclude from recognition as ligature patterns the following post mortem features [9]: Normal skin creases (especially infants and the elderly); Collar marks, necklaces, and other items found around the victim's neck which leave marks during the decomposition process. These should all be carefully distinguished from articles that were intentionally tightened around the victim's neck by an assailant. Gresham[6] shows two specific examples infants who died of accidental strangulation due to the edge of a garment constricting their neck. A corresponding ligature furrow was reflected in the skin.


PETECHIAE & OTHER SIGNS OF TRAUMA

There are associated physical evidences of traumatic asphyxia which can often be easily visibly identified in conjunction with ligature strangulation. Petechiae are often present on the victim([1], [3], [4], [5], [6], [7], [9]). Because veins are normally at lower pressure than arteries, traumatic injuries from an offending force to the neck(i.e. -ligature strangulation) cause an increase in venous pressure and an increase in capillary pressure that then causes damage to the inner walls of those capillaries. This damage produces minute points of bleeding which can be visible as pinpoint hemorrhages in the softer tissues. These minutes points of bleeding are called petechiae[3].

Look for scleral hemorrhage and petechiae in the eyes and insides of the eyelids[4]. Also look for petechiae in the cheeks and neck at or above the ligature furrow. Another place to look for petechiae is inside the nostril on the nasal membrane. The nasal mucosa is often overlooked by even trained pathologists for presence of petechiae.

Petechiae are not to be confused with freckle-like Tardieu spots. These are seen in hanging cases as, with time, punctate hemorrhages occur due to hydrostatic rupture of the vessels from blood pooling in the forearms, hands, and legs. Petechiae are much more minute, and associated with the soft tissue areas in the neck and head.

Also possible but not necessary is a bloody discharge from the nose and mouth of the victim. The presence of such a discharge is indicative of some kind of trauma. Absence of such a discharge from the victim should not be given a great deal of investigative weight in either direction.

OTHER EVIDENCE

As DiMaio[4] points out, hair is often found clutched in the hands of victims of ligature strangulation. The victim's hands should always be examined for evidence of any hair, fiber, or biological trace. Anything found should be documented and collected properly.

Fingernail clippings should be collected as well, but this is generally done by the ME or Coroner. The victim may have gouged her assailant and his skin may have collected under her nails. DiMaio mentions this but suggests that it "virtually never" occurs. This author is aware of a case in Connecticut where not only was tissue evident beneath a victims fingernails, but there was enough for a PCR DNA analysis. In that case, the DNA evidence was a deciding factor. It may be in the Homicide detectives best interest to suggest that the ME or Coroner to specifically look for the suspects tissue after taking the nail clippings if there is any question at all.

The hands of any victim at a homicide scene should always be bagged with paper bags, not plastic, to preserve any hair, fiber, or biological trace/transfer evidence.


DIFFICULT CASES

There are always cases which can at first confuse or mislead homicide investigators. Absence of visible physical ligature patterns does not automatically exclude the possibility of ligature strangulation. At autopsy, the internal examination of the body will tell a more complete story. Although atypical, these cases should be kept in mind when trying to recognize homicidal ligature patterns:

Case#1

"The body of a polish woman was found hidden behind the hedge bordering the famous Wrotham Hill, Kent, 'beauty spot'. Broad cloth-type pressure marks were drying out brown in the skin across the front of the neck and asphyxial changes were present - but no ligature. It was later found that a lorry driver strangled her with a woolen vest held tight from behind."[7]

Case#2

"The body of a 33 year old man was found lying face down on a country track. Although the first police officer on the scene had been concerned, the consensus view of CID officers and the police surgeon, after examining the body, both and the locus and stripped of clothing at the police mortuary, was of sudden natural death.

The case was referred for routine Medicolegal necropsy the following day...There were florid petechiae over the eyelids and conjunctivae. There were no externally apparent neck injuries. Neck dissection revealed bruising...The thyroid cartilage and hyoid bone were intact. There were florid mucosal hemorrhages, ranging from 1-7mm, over the lateral and anterior walls of the oropharynx and posterior surface of the epiglottis. On the right side of the tongue was an area of hemorrhage 8mm in maximum dimension. Dissection of the back revealed fresh bruising within the back muscles... Toxicological analyses were negative. The cause of death was given as strangulation."[4]


DOCUMENTATION & COLLECTION

Once ligature patterns have been identified, they must be properly documented and collected. Generally, it is going to be the purview of the Coroner or Medical Examiner to take the defining photographs of the ligature patterns and make them available to Homicide investigators. That office may also dissect, remove, and preserve the ligature in solution for later examinations. Removal and preservation of the ligature are not always routinely done, so investigators may want to request it if they think it's necessary.

PHOTOGRAPHY

Investigators should direct their own photographers to get in there and take some good close-ups of the victims neck from several angles before releasing the body. You can never burn enough film at a homicide scene. And investigators will want their own set of photos of the ligature pattern, separate from the ME's. In cases where the ligature is still present, investigator's will need detailed representations of the ligature in situ for any later reconstruction.

Additionally, take several shots documenting the nature of the ligature or ligature pattern with a Polaroid. In traumatic injury, the shape of the skin injury reflects that shape of the thing that caused it[3]. The ligature furrow is going to have the general shape of the ligature that made it. That's what you're looking for at the scene, and at any connected scene. If you don't have the ligature still present on the victim's neck, use the Polaroid's as a search tool. Investigators can walk around with the pictures in their hands while conducting a search of the scene, looking for a ligature that could have made the pattern in the picture.

The detail of the ligature pattern is not always clear to the eye. It may be possible to enhance the detail of the ligature pattern in these instances for photographic purposes using either side-lighting techniques or exposure of the pattern to UV light.

REMOVING THE LIGATURE

If it is not absolutely necessary to remove the ligature at the scene, then leave it in place. Document it with photographs. Make drawings of any knots. But leave it in tact if possible. It will come back from autopsy with the victim's clothes, and from there it can be submitted to the lab for any subsequent trace analysis depending on local departmental procedures.

If for any reason it is necessary to remove a ligature from a victim before the body is released into the custody of the ME or Coroner, take care to follow these next guidelines carefully([5], [9]), after photographing in context and close-up:

1. Any knots should not be disturbed or loosened.

2. A fixed ligature should be cut off and the ends immediately re-attached with string.

3. If the ligature consists of several parts, then each part should be cut off and immediately re-attached with string.

4. Document each successive step with photographs.

5. Photograph the removed ligature next to the pattern it created on the victim's neck.

6. Provide a detailed account of the nature of the ligature to the Coroner or ME, and make sure that office receives a set of photos.

We want to preserve the ligature, and any knots present in it, for later reconstruction. The ligature itself and the knots used to tie it may present special identifying features that are important to indicating the type of person or persons who used it. The precise dimensions of any disassembled ligature should be re-assembled after removal and re-photographed for easy comparison to its ligature pattern.

LOOK UNDER THE BODY

For seasoned investigators, this may be obvious. But the obvious is so often overlooked that it bears repeating, if only for the benefit of those who have investigated relatively few homicides.

When a murder has been committed, the body is often left in the position in which it expired. After the ME or Coroner takes custody of the body, investigate the area beneath it for further evidence. Unless the assailant moves the body himself, he is not going to know what he is leaving behind underneath it.

In any number of cases, including ligature strangulations, evidence left behind at the scene beneath the victim's body has included: business cards; scratch paper with phone numbers/notes/personal appointments; wallets; inscribed jewelry; used condoms; personal identification (i.e. - driver's licenses); etc. Any one of these things has enormous evidentiary value. Look under the body after the ME or Coroner takes it into custody.


COMPARISON & INDIVIDUALIZATION

Physical comparisons and individualization's of ligature patterns will serve a number of important applications for Homicide investigators:

1. A particular pattern can be linked to another particular pattern, as in serial cases.

2. A particular pattern can be linked to a ligature in the possession of a suspect.

3. A particular ligature can be excluded as the origin of a known ligature pattern.

4. A list of suspected ligatures can be generated in cases where the ligature is not immediately apparent.


CHARACTERISTIC LIGATURE IMPRESSIONS

As stated several times earlier in this work, the ligature furrow will be a reflection of the thing that made it. An electrical cord will not leave the same impression in the skin as a metal chain. A shoelace will not leave the same impression in the skin as a copper wire. A clothesline will not leave the same impression in the skin as a belt. And even within a class of one of these items, there is going to be a great deal of variability as to the nature of the ligature pattern.

Vanezis[9] states that close examination of a ligature pattern with a hand lens may reveal a distinctive pattern, or occasional fibers, that enable comparison with a suspected ligature. If a rope was used, the weave of the rope may be visible[3], as well as rope fibers. Chains and belts leave their own highly characteristic patterned abrasions on the victim's neck[3]. Soft ligatures made of folded cloth, like bedsheets, shirts, or sweaters, will leave abrasions and compression marks characterized by multiple irregular patterns that reflect the shape of the bunched cloth[3]. They may also leave fiber trace that can be chemically examined and/or microscopically matched for type and color to a suspected ligature.

Adelson[1] shows photographs of one 22 year old female victim who was strangled to death with her own brassiere. In situ, the brassiere is tightly knotted and there is associative bloody discharge from the victim's mouth. In a subsequent photograph with the brassiere removed, what remains as a reflection of the ligature is a bunching of the skin in a compression pattern. If the ligature had not been present on body at the scene, it may not have been as easily linked to the victim's ligature pattern. A search for bloody clothing, and perhaps later fiber analysis, would have been the investigators best tools for developing leads on possible ligatures to look for.

Gresham [6] shows photographs of a young male victim who was strangled with a lanyard. The assailant secured the ligature from behind the young boy and pulled tightly, leaving only a partially circumferential ligature pattern on the neck. Close examination of the ligature pattern is reveals a corrugated, characteristic furrow. A photograph of the actual lanyard alongside the ligature pattern on the victim's neck leaves little question as to the origin of that pattern.


RECONSTRUCTION

The reconstruction of a case is not always going to be a direct recreation of a logical sequence of events. Often it is a series of pictures drawn in terms of what was occurring at a given space at a given point in time. This done by analyzing all of the bits of physical evidence that have been collected from a crime scene, and attempting to reconcile them with each other without mutual exclusion.

The following are a set of useful reconstructive tips garnered from the literature that may help to illuminate some of the features of ligature strangulation with a detail or two.

 

THE LIGATURE

The ligature itself is of great importance. What was used? Was it something that the assailant brought with him to the crime scene, or did he acquire the ligature at the scene? This speaks to premeditation, organization, and intent.

In one case we have brassiere being used. Was this something that the assailant brought with him to the scene, thinking that it would be the most effect ligature? That is highly unlikely. Is it then more or less likely that the offender planned to specifically strangle the victim before he got to the crime scene?

In another case we have a lanyard being used as a ligature. Did this offense occur on a boat, or was this something that the assailant would have had to bring with him to the scene? If he did bring the lanyard or any other particular kind of ligature, what does it say about an assailant?

The choice of ligature has significance. It should not be dismissed lightly. Establish how and perhaps why it got into the crime scene.

 

THE KNOT

The ligature is usually drawn once or twice around the neck and pulled tight until unconsciousness or death occurs. There will be a break in the ligature furrow at the point where the assailant's hands were. If there is a knot or tourniquet impression on the neck of the victim, and no ligature is present, then the ligature was, at some point after the victim's death, untied and removed.

Now ask some questions of the knot or tourniquet: How tight was it? Could the victim have accomplished it themselves(suicide)? Is this something that took some time to think about and put together, or was it done in a hurry with materials found at the scene?

Note the nature and complexity of any knots or tourniquets, and try to identify them if possible. It may be possible to generate a narrow suspect pool from the type of knot used. In cases of suicidal strangulation, a single knot is almost always used. The tourniquet method, however, is used in both homicide and suicide cases. Remember also that the tourniquet method takes time to implement on an unwilling victim.

The term garroting is applicable in situations where a victim is attacked from behind without warning, overpowered, and killed[9]. There is very little time or assailant/ victim interaction. If an assailant employs a more time consuming method, what does this say about his perceptions of time? If the assailant attacks and kills with very little interaction with the victim, what does that say?

When thinking about the knot or tourniquet or the nature of the ligature itself as applied to the victim, the two most important questions to ask are: 1)What did the assailant take time to do? 2)What did the assailant not take time to do? This will establish what was important or not so important to this assailant during the attack.

 

THE LIGATURE PATTERN

Vanezis[9] gives an introduction to the issues of interpreting the ligature pattern:

"It is not unusual in homicidal ligature strangulation to find that there is more than one ligature mark, each of varying intensity and crossing each other, in parallel or at an angle to each other. Together with such an appearance, one quite commonly sees abrasions caused by movement of a ligature across the neck, or associated fingernail marks, either from the victim attempting to remove the ligature or (together with finger- tip bruising) from the assailant attempting to secure the ligature and/or restrain the neck from moving or even attempting manual strangulation. The victim's clothing or necklace may also be caught in the ligature during a struggle and marks from these require careful evaluation."

In agreement with Vanezis, DiMaio et al[4] adds:

"The appearance of a ligature mark on the neck is subject to considerable variation, depending upon the nature of the ligature, the amount of resistance offered by the victim, and the amount of force used by the assailant. The ligature mark may be faint, barely visible, or absent in young children or incapacitated adults, especially if the ligature is soft, for example a towel, and removed immediately after death. If a thin ligature is used, there will be a very prominent deep mark encircling the neck. Initially, it has a yell parchment-like appearance that turns dark brown."

The pattern that is found on the neck will tell investigators what occurred, or what did not occur as the victim was being strangled with the ligature by the assailant. Behaviors of both the assailant and the victim can contribute to the formation of this pattern. With these two unpredictable forces at play, the force used to apply the ligature, although important, is best gathered from an internal examination[9].

The length of application is not very reliably externally assessed in these cases either[9]. The best general idea of a length of application is not from the ligature pattern itself, but from the presence or absence of associated injuries on the face, neck and hands on the victim. Look for abrasions along the ligature furrow, or pattern overlapping, which may indicate victim struggling or victim movement of some kind. This may also be indicative of an offender re-wrapping the ligature to get a better hold. Any of these things tend to add to the duration that a ligature was applied to a victim's neck before death.

Additionally, look for other injuries to the victim's person. What were the nature and extent of the injuries? Did the assailant have to injure the victim in addition to the strangulation? This will give the investigator a good overall understanding of the general necessary victim/ assailant interaction time.


SERIAL CASES AND LIGATURE

In cases of complex ligature, or ligature that goes beyond the functional role of subduing, controlling, or killing the victim, special attention should be paid. The type of knots or method of knotting, the number of wraps or knots, the tightness of the ligature; these things can be used to establish an assailant's signature during a crime, or even help establish his or her identity. A good question to ask about the ligature itself is whether it is something that could be accomplished with little thought, or is it the type of ligature that would take practice to do well. Over time, this assailant will not change certain features of his assault on his victims. Complex ligature, which is practiced and learned, is one of the areas to look for this repetition.


INTENT

A final note on intent. Although almost always homicidal, ligature strangulations are not always intended by the assailant[7]. The ligature may be thrown around the victim's neck perhaps only to subdue or to silence. The onset of unconsciousness is only 10 to 15 seconds. The victim's death can come very suddenly after. If it can be demonstrated that the ligature was drawn relatively tight in a short period of time, this might tend to be more directly supportive of intentional homicide.


CONCLUSION

The successful investigation and reconstruction of cases involving ligature homicide cannot be accomplished by one interest alone. The homicide investigator must have the cooperation and input of everyone involved, from the crime scene photographer to the Medical Examiner or Coroner. The collection goals of the investigation must be defined early on, and the evidence must be collected with care and deliberation. Without competency in these considerations, a successful investigation and reconstruction of any homicide is difficult.

In cases involving ligature strangulation, care must be taken in recognition and documentation of ligatures and ligature patterns, for more accurate comparison, identification and reconstruction of the evidence. Care must also be taken in the physical analysis of associative injuries indicative of trauma, such as petechiae, especially in the absence of an immediately visible ligature and ligature patterns. Tendering to these and the other specific considerations involved in cases of ligature strangulation, the homicide investigators can hope to reconstruct a more competent reflection of the facts initially presented to them at a given crime scene.


BIBLIOGRAPHY

1)Adelson, Lester, The Pathology of Homicide (Springfield, Ill: Charles C. Thomas, Pub., 1974), pp.552-553

2)Anagnostakos, Nicholas P. & Gerard J. Tortora, Principles of Anatomy and Physiology, 4th Ed., (New York: Harper & Row, Publishers, 1984)

3)Carver, H. Wayne, II, M.D., Chief Medical Examiner, State of Connecticut, "Traumatic Asphyxia," Article handed out during lecture in UNH course entitled Medicolegal Death Investigation and Identification, May 3, 1995

4)DiMaio, D, & DiMaio, V., Forensic Pathology, (Boca Raton: CRC Press, 1993), pp. 246-247

5)Geberth, Vernon, Practical Homicide Investigation, 2nd Ed., (Boca Raton: CRC Press, 1993)

6)Gresham, G. Austin, Color Atlas of Forensic Pathology, (Chicago: Year Book Medical Publishers, 1975)

7)Knight, Bernard & Simpson, Keith, Forensic Medicine, 9th Ed., (London, UK: Edward Arnold Publishers, Ltd., 1985)

8)Sadler, D.W. "Concealed Homicidal Strangulation First Discovered at Necropsy," Journal of Clinical Pathology, 1994; 47: 679-680.

9)Vanezis, Peter, Pathology of Neck Injury, (Somerset, UK: Butler & Tanner Ltd., 1989)


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