Use of Alternate Light Source/Negative Invert Filters to Improve Visibility of Injuries Under the Skin

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90 Minutes

Originally Aired
August 22, 2013

We are delighted that SPEX Forensics sponsored this webinar. SPEX Forensics is a manufacturer of world-class forensics products including: Crime scene and Laboratory Supplies, Forensic Light Sources, Reflective Ultra Violet Imaging Systems, Fingerprint Image Enhancement and Identification Systems. The World Leader in Forensic Light Sources, SPEX Forensics is the manufacturer of the “Ultimate Forensic Light Source,” the CrimeScope Series. This line of high-power, versatile light sources are highly effective in finding many different types of evidence including injuries on victims both living and deceased and are an invaluable tool in finding evidence not normally seen with the naked eye. Contact them for a no obligation, onsite demonstration at

Diana Faugno
Debra Holbrook, R.N., SANE-A, FNE A
Rachell Ekroos
Rachell A. Ekroos, PhC ARNP-BC AFN-BC

Strangulation is a common form of intentionally inflicted injury on victims of interpersonal violence. Unfortunately, this type of injury has often been overlooked by both medical providers and law enforcement professionals. This is due to the fact that most injuries incurred from strangulation are not visible to the naked eye. While external signs and symptoms of strangulation and other injuries may be difficult to detect with the naked eye, new technologies are available to assist in visualizing these underlying physical injuries. These new technologies include alternate light sources (ALS), digital software filters, and the use of digital photodocumentation to capture images visible with the assistance of ALS.

During this webinar the presenters will discuss ALS technology, negative invert filter software, and digital photodocumentation as each relates to patients/victims who have been strangled or physically abused. These technologies can be used by medical professionals at the time of an exam or by law enforcement professionals with assaulted persons who do and do not seek medical treatment. In addition to physical injury visualization, ALS technology may be used to identify dried fluids (e.g. semen, blood, urine) and other evidence (e.g. fingerprints) that can be collected for forensic analysis. Without these technological tools many of the samples might otherwise go undetected under standard lighting conditions.

The presenters will also provide an overview of each technology, implications for use, and review current research investigating how ALS technology can be been used with patients reporting strangulation and other forms of injury. Case examples will also be discussed.


At the conclusion of this session, participants will be able to:

  • List 3 external physical symptoms observed in strangulation cases
  • Describe 3 differences between the ALS and negative invert filter technologies
  • Describe the application of ALS and negative invert filters to patients/victims reporting strangulation
  • List 3 challenges in using photodocumentation with ALS technology
  • Explain how using a tool to enhance visualization of an injury is different than diagnosing an injury

Not Just for Nurses

We also want to emphasize that this webinar is not just for forensic examiners! These techniques can also be used by law enforcement professionals in the field, to view and document injuries among victims who do not have a medical forensic examination. There are countless other applications as well, but it is important to develop a foundation of knowledge in these technologies so you can use them.


EVAWI is approved by the California Board of Registered Nursing to provide Continuing Education contact hours for nurses (Provider #15641).

Registered Nurses may purchase 1.5 contact hours after completing this webinar.

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