Blue Line

Investigating strangulation

February 12, 2014  By Peter Keen

Strangulation is a common method of assault in domestic violence but in many cases there is little physical evidence. It is also very dangerous, posing a significant risk to the life and health of victims. Unfortunately, unless there is some serious physical injury, police, prosecutors and the courts often treat cases as minor.

This article explains how front line officers can investigate and document strangulation cases where the victim survives, helping to ensure these offences are treated seriously and attract appropriate sentences.

The problem – strangulation is common, potentially lethal but often inadequately investigated

Studies reveal strangulation is a common form of assault in domestic violence. Between 23 per cent and 68 per cent of domestic violence victims report being strangled <1>. It is also potentially lethal, with several U.S. reports indicating it is a common cause of death in domestic homicides <2>.

In Canada, strangulation, suffocation or drowning was the cause of death in 18 per cent of domestic homicides and 22 per cent of child homicides between 2000 and 2010 <3>. It may also be a significant risk factor for future violence and homicide <4>.

Despite the danger and frequency with which it occurs, studies have revealed problems with both investigation and prosecution of strangulation. Many police reports fail to document the nature of the assault and symptoms <5>. Gael Strack and George McClane, who studied strangulation in San Diego, noted that:

<Sadly, our study showed that unless the victim had significant visible injuries or complained of continuous pain requiring medical attention, the police handled the incident as though she had been slapped in the face rather than strangled> <6>.

The problem appears to be similar in Canada, with a 2006 Uniform Law Conference study indicating that there is a need for improved police training in this area <7>.

Officers may have observed that strangulation cases, particularly where there is no significant injury, are being treated as ‘minor’ or ‘routine’ by prosecutors and the courts. Officers may have observed that other criminal justice system participants fail to recognise the seriousness of a strangulation allegation. They need to understand what strangulation is and the symptoms that may result to properly investigate.


Strangulation is compression of the neck with or without blockage of the airway. It is a type of mechanical asphyxia resulting from direct external pressure to the neck. Asphyxia can be defined as ‘absence of a pulse’ or, more commonly, the absence or lack of oxygen. It is a general term encompassing a variety of conditions that result in interference with the use or uptake of oxygen at the cellular level.

Since oxygen is essential to sustain life, a reduced concentration reaching the brain results in a rapid loss of consciousness. For practical purposes, asphyxia is categorized into four categories: compression of the neck; obstruction of the airway; compression of the chest; and exclusion of oxygen due to a depletion and replacement of oxygen by another gas.

Strangulation may occur with or without blockage of the airway <8>. It can close the blood vessels (carotid and/or vertebral arteries) supplying blood to the brain, comparable to a hose being compressed. Another mechanism would prevent oxygen from entering the lungs by closing the upper airway (trachea). These may occur separately or simultaneously.

Strangulation can be very dangerous. It takes a mere 11 pounds of pressure on the throat for 10 seconds to render someone unconscious. Unconsciousness is caused by constricting blood flow to the brain. Death can follow within minutes if the pressure is not released.

Strangulation can be caused by the use of hands, the constricting pressure of a ligature around the neck or other solid objects. Manual strangulation can result from applying one or both hands onto the neck. If a ligature is used, it can be of a simple nature, such as a zip tie, rope, belt, curtain cord or electrical extension cord.

Other types of strangulation involve arm-locks, choke-holds, carotid-sleeper holds or the use of a solid stick such as a broomstick or baseball bat, which may cause unrelenting pressure on the trachea and external jugular veins.

Hanging is also a form of ligature strangulation but the difference is that the force applied to the neck is derived from the gravitational weight of the body.

Where the victim dies from manual and ligature strangulation, death is caused by the compression of the internal structures of the neck by the occlusion (blocking) of the carotid arteries and external jugular veins. Occlusion of the airway plays a minor role, if any, in death.

{Physical evidence}

There is often physical evidence present where the victim dies from strangulation and it may also be visible in a living victim. Officers confronted with an allegation of strangulation should look for physical signs of strangulation, which include:

  • Bruising may be observable on the front, sides or back of the neck, angles of the jaw, chin or as far down as the collar bones (clavicles) or even below. Bruises may be discoid and one to two centimeters each in diameter, representing finger pads clustered on one or both sides of the neck.

  • Abrasions may be present from fingernails on the throat, which are characteristically semi-lunar or linear.

  • Petechiae (small pinpoint hemorrhages) may be seen in the skin and mucosal surfaces of the eyes. In some cases they may be visible throughout the entire face above the compression point. Petechiae arise from the increased venous pressure that arises from blocking veins in the neck.

  • Marks: Ligature strangulation displays a horizontal, almost circumferential, abrasion around the neck depending on the nature of the ligature used <9>.

  • Voice changes: Strangulation can cause changes in the voice. A victim may speak in a rough, hoarse tone.

{There are often no marks}

Although signs of strangulation may be present, this is often not the case. It can occur without any visible injury at all.
In a study of 300 strangulation cases in San Diego, there were no visible injuries in 50 per cent of the cases and only minor visible injuries in a further 35 per cent <10>.

{Non-visible symptoms}

Where there are no visible injuries, victims may still have experienced symptoms to which they can testify. Such evidence can, if recorded in the Crown brief or interpreted by medical practitioners, help prove the strangulation was objectively serious and even life threatening.

Non-visible symptoms of external neck pressure include shortness of breath, difficulty swallowing, coughing, cognitive changes (confusion, restlessness, agitation) and eventually loss of consciousness. In addition, symptoms can include a dramatic condition known as ‘air hunger’ in which a violent struggle is elicited by tremendous fear of impending doom coupled with violent efforts to open the airway <11>.

Symptoms may also come from hypoxia (lack of oxygen to the brain) or ischemia (lack of blood to the brain). These symptoms can include feeling faint, blurry vision, flashes in or out of consciousness, a sensation that a light is flickering, tingling in the extremities (fingers, hands, toes, arms and legs) and, of course, losing consciousness.

{Investigating with no physical symptoms}

Where there are no visible symptoms of strangulation, it will be important to collect as much concrete information as possible from the victim to assess how serious the strangulation incident was.

Domestic violence victims often minimize violence, particularly with the passage of time, or may simply be inarticulate, poorly describing the violence and symptoms experienced. As an example, a victim may simply say “I was choked” when giving a statement. If this isn’t followed up, the nature of the assault will be unclear.

As an example, the words ‘I was choked’ may simply mean the accused grabbed the victim’s throat to push her away, causing momentary and minor pressure to the throat.

“I was choked” may also mean the victim was thrown to the floor and the attacker wrapped their hands around the victim’s throat and squeezed until they blacked out while they kicked and fought back in panic, believing they were going to die. Inadequate questioning or follow up will fail to reveal the seriousness of the actions underlying the words “I was choked.”

The burden of proving aggravating facts in a criminal case is always on the state. This means that if the court hasn’t anything more than the words “I was choked” to go on, it is likely to treat the ‘choking’ as minor unless there is evidence it was objectively serious.

As such, it is important when victims indicate that they have been strangled, choked, or have suffered airway obstruction during an assault to clearly determine the nature of the assault. Document any injuries, collect available physical evidence and ask detailed questions so that prosecutors, courts, medical experts and victim advocates can know just how serious the strangulation incident was.

Officers should ask detailed questions about the nature of the strangulation and the symptoms experienced even if there are no injuries – questions such as:

  • How did the strangulation occur? (Get victims to show their and their attacker’s position.)

  • Did you feel dizzy, faint, or lose consciousness?

  • Did your level of consciousness change during the assault?

  • How did your hands and feet feel – was there any tingling in them?

  • Were there any changes to the appearance of light while this was occurring?

  • Was an object used to strangle you (a rope, belt or towel, for example)?

  • How much pressure did the suspect use? (This is difficult to assess in every individual. A general answer would be ‘a little, a lot, too much that it hurt’).

  • Were you coughing afterwards?

  • Did you have any problem breathing afterwards?

  • Did you defecate or urinate as a result of the assault?

  • Did you have any pain to your throat?

  • Did you feel nauseous or vomit?

  • What did the suspect say during the assault?

  • Was anything else being done to you while you were strangled?

Carefully record both the answers and any observable symptoms such as redness around the neck, ligature marks and so on. Take photographs at the time and follow up photographs later, as some injuries, such as bruising, may become more visible over time. If the victim’s voice has changed as a result of the attack, record them speaking to document the change.

Lastly, don’t forget that there were two people present during the assault. Try to take a statement from the suspect and use your knowledge of symptoms when doing so. For example, ask the suspect:

  • Did the victim stop resisting?

  • What did the victim’s face look like during choking?

  • How did the victim react after you stopped choking them?

  • Did the victim appear to lose consciousness?

Consider collecting other pieces of evidence. Examine for physical evidence, take photographs of the scene and seize items that were used during the struggle.

{Charges other than simple assault}

There is a ‘choking’ charge available at <s. 246> of the Criminal Code. It can only be laid where the accused has choked, suffocated or strangled someone for the purpose of overcoming the victim’s resistance to commit some other indictable offence beyond the strangulation, such as a sexual assault or robbery. The key element of the offence here is proving that the accused had some purpose beyond the strangulation itself <12>.

A <s. 246> charge will often be inappropriate because the strangulation is the assault and no other ‘purpose’ can be identified. In such cases, the only charges that may be available are one of the levels of assault (<s. 266, 267> or <268>). Where a weapon is used to commit the strangulation, an assault with a weapon charge can be laid. Where there are injuries that amount to bodily harm, an assault causing bodily harm charge can be laid. Where those injuries amount to wounding, maiming or disfigurement, aggravated assault charges can be laid.

Additionally, even if there are no visible injuries, officers should consider laying an aggravated assault charge if the victim’s life was endangered. This may occur if the victim reports a loss or change in consciousness due to the assault or reports objectively serious symptoms. It may seem common sense that strangulation may endanger life and a court may be willing to infer that life was endangered from the strangulation <13>, however there is no rule that a court must draw such an inference. Some courts may be reluctant to do so in the absence of supporting medical evidence.

You should always obtain emergency room and other medical records pertaining to the assault but they will often simply describe the injuries, symptoms and diagnosis. They may not, on their own, explain the severity of the assault or clearly articulate whether life was endangered. Accordingly, if you are considering an aggravated assault charge, consider obtaining expert medical evidence that addresses the nature. There are several potential sources, including emergency room physicians, other medical doctors and expert forensic witnesses such as forensic pathologists.

Doctors and pathologists can review police evidence – including victim statements, medical records and documentation of weapons and injuries – and may be able to relate symptoms to physiological causes. By way of example, a doctor may review documentation revealing: the victim reported being strangled and nearly passed out; felt tingling in hands and feet; and perceived light fading or flickering.

A doctor may be able to testify that such symptoms can be caused by the brain not receiving sufficient blood or oxygen, which places life at risk. He/she may also be able to explain the dangers associated with strangulation and what symptoms such as blacking out, tingling of the hands or feet, or loss of bladder control mean in a strangulation episode. Such evidence may help establish that the victim’s life was endangered.


Every strangulation case begins with an investigation. Evidence collected from the victim at the time of the incident, including the details of the strangulation and the symptoms the victim experiences, is vital. The quality of work by frontline officers, responding to routine domestic assault cases, will have a tremendous impact on how seriously prosecutors and judges will treat the case.


  1. Gwinn, Casey and Strack, Gael, “Background Information for a California Strangulation Statue,” National Family Justice Center Alliance Strangulation Training Institute, January 2011; Fact Sheet, Strangulation Assaults in Domestic Violence Cases, The Center on Family Violence.

  2. Supra, see also Schwartz, Amy, “Strangulation and Domestic Violence: Important Changes in New York Criminal and Domestic Violence Law.” Empire Justice Center, November 19, 2010.

  3. Family Violence in Canada: A Statistical Profile, 2010, Released May 22, 2012, Statistics Canada, p. 38, Chart 2.8; p. 78, Table 3.3

  4. Supra, notes 1 and 2; Report of the Criminal Section Working Group on Strangulation, Uniform Law Conference of Canada, May 2006 (ULCC)

  5. Strack, Gael et. al. “How to Improve Your Investigation and Prosecution of Strangulation Cases,” updated May, 1999 (October 1998),

  6. Strack, Gael B. and McClane, Dr. George, “How to Improve Your Investigation and Prosecution of Strangulation Cases” (October 1998),

  7. See for example, the ULCC paper, supra

  8. Spitz and Fisher’s, Medicolegal Investigation of Death, Charles C. Thomas Pub. Ltd, 4th ed. p. 783

  9. Spitz and Fisher, supra note 9, p. 787

  10. Strack, Gael B. et al. “A Review of 300 Attempted Strangulation Cases : Part I : Criminal Legal Issues,” Journal of Emergency Medical Medicine, Elsevier Science Inc., Vol. 21, No. 3, October 2001, cited in Report of the Criminal Section Working Group on Strangulation, Uniform Law Conference of Canada, May 2006

  11. Spitz and Fisher, supra note 9, at p. 791

  12. (2009) O.J. No. 4253 (Ont. C.J.); R v. Heddon, 2006 CarswellAlta 1818 (AB. Prov. Ct.);

  13. See for example R v. Sayers, (2008) O.J. No. 3516 (Ont. C.J.)


Peter Keen is an assistant crown attorney with the Ontario Ministry of the Attorney General. Dr. Anita Lal is a forensic pathologist with the Ontario Forensic Pathology Unit.

Print this page


Stories continue below