EXPIRATED BLOOD

• Jurisdiction: Australia

[97.1400] Overview

The experienced bloodstain pattern analyst is familiar with the characteristics, shapes and sizes of bloodstains associated with blunt force assaults. In addition, the examiner will have an expectation in respect of the likely blood staining on the clothing of such an assailant.

A difficulty arises when the suspect has had legitimate cause to be close to, or in contact with, the victim. Consideration must then be given to alternative mechanisms for blood deposition on the suspect's clothing: Loveday (1991). For instance, blood found on a suspect's clothing may have been expirated from the mouth or nose of the victim through the action of breathing; including coughing or sneezing. Coughing may be a result of blood in the nose, mouth or throat but is more likely to be a reflex coughing action precipitated by a stab wound into the lung or by an obstruction in the throat. An adult at rest breathes in (inspirates) approximately half a litre and breathes out (expirates) the same amount about 12 to 14 times per minute. The breathing cycle is not linear and the air flow peaks and fades within each cycle. A cough varies from normal expirated air in its ferocity as the effect of a cough forces out a short air pulse at a rate of 20 to 50 litres (L) per second. This issue was pivotal to the Jenkins matter in R v Sion Jenkins (English Court of Appeal...