Toxicological analysis after asphyxial suicide with helium and a plastic bag
V. Auwaerter*, M. Grosse Perdekamp, J. Kempf, U. Schmidt, W. Weinmann, S. Pollak
Institute of Legal Medicine, University Hospital Freiburg, Albertstr. 9, 79104 Freiburg, Germany
Received 9 October 2006; received in revised form 1 March 2007; accepted 2 March 2007
Available online 12 July 2007
A 23-year-old man was found on a raised hide in lying position, the head wrapped in a plastic bag connected with a helium gas cylinder by a
polypropylene tube. The autopsy did not show any specific findings nor did the routine toxicological analysis reveal significant information
regarding the cause of death (BAC 0.9 mg/g, diphenhydramine 0.81 mg/ml in heart serum). For the detection of helium in the lungs, gas samples
frombothlungswerecollectedby amethodensuringminimaldilution.Gas analyseswereperformedusingaGC–MSwithasplit–splitlessinjector
and a headspace syringe. As carrier gas the commonly used helium was replaced by nitrogen. Helium was found in clearly elevated concentrations
in gas samples from both lungs. Therefore, suffocation by breathing helium enriched, and thus oxygen deficient atmosphere, can strongly be
assumed as the cause of death.
# 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Suicide; Asphyxiation; Helium; Headspace GC–MS; Post mortem analysis
deficient gas atmosphere are described in literature, e.g., [1–5].
Among them there are cases ofaccidentalsuffocation aswell as
cases of suicide. In the last years, right-to-die activists
promoted suicide methods by asphyxiation with use of gases
as being relatively quick and painless . These methods leave
hardly any post-mortem evidence, and therefore, raise a serious
challenge for police authorities and analysts. As these ideas are
quickly spread in Internet threads, it can be assumed that
in future a growing number of similar cases will occur.
Technically important gases with low toxicity and a pre-
dominant suffocating effect are helium, argon, nitrogen and
methane. The analytical detection of these gases requires great
efforts in regard to sampling and careful choice of analytical
techniques. In most of the cases described in literature no
analytical evidence was supplied.
2. Case history
A 23-year-old man was found dead on a raised hide in lying
position. A plastic bag connected to a helium gas cylinder by a
polypropylene tube was put over his head and fixed with a
rubber band. An almost empty bottle of tequila and a blister
pack of a drug against travel sickness containing diphenhy-
dramine as well as a pack of ibuprofen tablets were found next
to the body. Considering the scene it was assumed that helium
assisted asphyxiation could have been the cause of death.
During autopsy, unspecific signs of intoxication including an
aqueous swelling of the brain and of the lungs and an acute
hyperemia of the kidneys were noticed but no evidence of
severe illness or injury could be found. The routine
toxicological analysis showed a BAC of 0.9 mg/g and
diphenhydramine was found in heart serum (0.81 mg/ml) and
urine (2.2 mg/ml). Ibuprofen was found in urine and in the
3. Material and methods
3.1. Collection of gas samples
During autopsy both lungs were subsequently collected in a plastic box
filled with water. The box was covered with a lid, leaving as little air as possible
in the box. The box was turned upside down, and using a syringe fitted with a
T-piece, the residualairwas suckedout ofthe box and discarded.Then longand
thick metal needles were pierced into the side of the box to manipulate the lung
and press out the gas. The gas volumes escaping from the lung were collected
with the syringe from one corner of the box and were pressed into a headspace
vial which had been filled with water and crimped closely before. For this
purpose the septum of the vial cap was punctured with a second cannula, and
Forensic Science International 170 (2007) 139–141
* Corresponding author. Tel.: +49 761 203 6862; fax: +49 761 203 6858.
E-mail address: firstname.lastname@example.org (V. Auwaerter).
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holding the vial with the bottom up when filling the gas sample in via the
septum, the water was displaced through the second cannula. The sampling
procedure is illustrated in Fig. 1. For comparison, the same procedure was
carried out with another autopsy case without pre-mortal exposure to helium
In order to get an impression of the helium concentrations in the lungs
reached by inhaling pure helium gas and for the purpose of method control a
volunteer deeply exhaled and then inhaled helium once. Directly after a part of
the exhalation gas was collected into a headspace vial which was crimped
closely immediately. The samewas donewith the breath of the second and third
exhalation. All samples were analyzed for helium using headspace GC–MS in
selected ion monitoring (SIM) mode.
Gas analyses were performed using a GC–MS with a split–splitless injector
(HP 5890 GC/5970 MSD, split ratio 3:1, flow 1 mL/min, injector temperature
100 8C, oven: 120 8C isothermal, interface temperature 200 8C, SIM: m/z = 4,
16, 18, 32, 40, 44) and a headspace syringe (manual injection, injectionvolume
500 mL). The GC column used was an Optima11 MS (Macherey-Nagel,
Du ¨ren, Germany; i.d. 0.25 mm, film thickness 0.25 mm, l = 25 m). As carrier
gas the commonly used helium was replaced by nitrogen.
4. Results and discussion
In Fig. 2 the obtained chromatograms for a gas sample of the
case under investigation and the negative control case are
shown. The signal at 1.4 min in the left chromatogram
originates from helium as proved by injection of pure helium
beforehand. In the negative control (right chromatogram) no
helium was detected. Thus, the ante mortem inhalation of
helium was proven and suffocation by breathing helium
enriched, and therefore, oxygen deficient atmosphere can
strongly be assumed as the cause of death.
From the helium inhalation experiment it can be seen that
after three breathing cycles most of the inhaled helium gas is
already exhaled (Fig. 3). This finding confirms that rapid loss of
analyte can be a serious problem in cases with suspected gas
inhalation. Therefore, sampling has to be carried out as soon as
possible after the incident and measures have to be taken to
avoid further loss of analyte during the sampling process.
In general, the analytical detection of the suffocating gas is
recommended in death cases with suspected involvement of
technical gases because it provides a higher certainty in the
evaluation of an assumed cause of death. Even if there is a
Fig. 1. Illustration of the sampling procedure.
Fig. 2. Headspace GC–MS–SIM-chromatograms of gas samples. (Left side)
Gas sample from the deceased, (right side) gas sample from a control case
without prior exposure to helium (same sampling procedure).
V. Auwaerter et al./Forensic Science International 170 (2007) 139–141140
longer time span between death and sampling (e.g., 3–5 days Download full-text
The presented HS–GC–MS method provides a suitable
technique for qualitative detection of helium in gas samples.
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Fig. 3. Headspace GC–MS–SIM-chromatograms of respiratory gas sampled
after three consecutive exhalations following a single inhalation of helium.
V. Auwaerter et al./Forensic Science International 170 (2007) 139–141141