Electrical excitability of skeletal muscle postmortem in casework

Area of Science:

• Forensic Science
• Physiology
• Postmortem Interval Determination

Background:

• Accurate determination of the postmortem interval is crucial in forensic investigations.
• Existing methods for estimating time since death have limitations.
• Postmortem electrical excitability of skeletal muscle offers a potential avenue for improved accuracy.

Purpose of the Study:

• To review the development of methods for assessing postmortem skeletal muscle electrical excitability.
• To propose a practical method for casework application in determining time since death.
• To evaluate the reliability of this method in various death scenarios.

Main Methods:

• Utilizing the orbicularis oculi muscle for electrode placement.
• Applying rectangular electrical impulses (10 ms duration, 30 mA, 50/s repetition rate).
• Grading muscular reaction into 6 degrees based on movement and contraction intensity to assign time estimations with 95% confidence limits.

Main Results:

• The proposed method provides time estimations with 95% confidence limits.
• These estimations were validated for cases of sudden natural or traumatic deaths.
• Factors like chronic disease, hypothermia, or hematomas can influence time estimations.

Conclusions:

• The electrical excitability method offers a viable approach for postmortem interval estimation.
• Combining this method with temperature-based methods (e.g., Henssge) enhances precision and accuracy.
• This integrated approach improves time of death estimations, particularly in the early postmortem interval.