The Forensic Science Behind Bruise Healing

Forensic health experts are often asked by the criminal justice system to identify the age of bruises in victims of violence. Using objective, forensic data to evaluate a victim’s bruises may help support or disprove an injury’s origin in a civil or criminal proceeding. To date, however, research in this area has been limited. A recent study led by Katherine Scafide, PhD, RN, an assistant professor of nursing at Georgetown University School of Nursing and Health Studies, provides a foundation for understanding how bruises change color as they age and how they heal differently based on gender, skin color, and the role of fat below the surface of the skin.


In this study, a final sample of 103 participants was used. The following are the assumptions and methods used to gather data.

The sample included English-speaking, healthy adults between the ages of 18 and 45. An upper age limit of 45 was used so that it wasn’t necessary to factor in the effects of declining estrogen on inflammation.

The sample excluded subjects who had:

Day 1


Color was measured objectively using a colorimeter, which converts reflected light into numerical values. After a baseline reading of skin color was done, participants were bruised in the selected, exposed upper arm with a paintball pellet on day one.


The subjects were positioned against a rubber-covered plywood opening where the arm was struck with a paintball pellet, 17 mm in size, from a distance of 20 feet.

30 Minutes Post Trauma

Thirty minutes after the paintball’s impact, the resulting skin discoloration was marked and colorimetry measures were taken.

Days 2 – 5

Healing Process

Study participants were observed for four consecutive days. Physical examinations of the bruises were done, weight was taken, body mass index (BMI) was calculated, triceps fat was measured, bruise size was determined, and a colorimeter was used to measure color. Individual Typology Angle (ITA) was used to categorize skin color. Participants were asked not to apply ice, massage the impact site, or take anti-inflammatory medication.


Average Participant

Females had a significantly higher amount of triceps fat.


0 days: All subjects developed a bruise within 30 minutes following the paintball impact.

1 day: Bruises were at their most blue approximately 24 hours after the initial trauma.

2 days: The size of bruises varied but typically decreased over time.

3 days: Between two and three days, the bruises had a greater concentration of yellow than skin color.

4 days: The darkness of a bruise doesn’t significantly change in the first four days.


Healing Process


Ethics Review

This study was conducted with the approval of the Johns Hopkins Medicine Institutional Review Board. The protocol was developed and reviewed in accordance with the ethical principles outlined in the Belmont Report and the United States Department of Health and Human Services Federal Policy for the Protection of Human Subjects. Written informed consent was obtained from each subject prior to participation.

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School of Nursing & Health Studies


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