Smart watches can help solve murders by determining time of death more precisely

A new study by the Netherlands Forensic Institute (NFI) has found that smartwatches can help pinpoint the time of death with a margin of just 30 minutes, making it the most precise method to date. The research, led by forensic physician-in-training Tanja Gosseling, was conducted under the guidance of digital forensic scientist Jan Peter van Zandwijk and forensic pathologist Bart Latten. The study examined patients undergoing medically supervised euthanasia.

"We can now establish the timeline of a death with even greater accuracy, which can be crucial in homicide investigations," Van Zandwijk said.

Gosseling’s research focused on analyzing physiological data recorded by smartwatches, including heart rate, movement, and in some cases, blood oxygen levels. “More and more people wear smartwatches,” she said. “When someone is found deceased, there are often questions about the cause and time of death. Data from a smartwatch can provide valuable insights.”

Van Zandwijk emphasized the forensic significance of this data. “These smartwatch readings can be a key source of information in criminal investigations and are also useful to law enforcement.”

Study on euthanasia patients

The study examined patients undergoing medically supervised euthanasia, allowing for a precise comparison between smartwatch data and the recorded time of death. At least three hours before the expected death, participants wore a smartwatch, which was removed approximately 30 minutes after passing.

The study tested three smartwatch brands: Garmin, Apple Watch, and Samsung Watch. Researchers then compared the collected digital traces to the exact time of death as documented by the attending physician.

Before proceeding, an independent medical ethics committee reviewed the study to determine whether it fell under the Dutch Medical Research Involving Human Subjects Act (WMO). Since participants were not subjected to invasive procedures or behavioral constraints, the committee ruled that WMO approval was not required.

A total of 27 individuals voluntarily participated in the study after being approached through their general practitioners. Each participant provided written consent. One participant's statement particularly resonated with Gosseling: “I think it’s wonderful that on the last day of my life, I can contribute to science and help others.”

Traditionally, forensic experts determine time of death using methods such as body temperature analysis, which can have an uncertainty margin of several hours due to external factors like clothing, air circulation, humidity, and ambient temperature. The smartwatch data reportedly allows for a significantly narrower time frame, improving accuracy in forensic investigations.

“This research is a first step in using smartwatch technology for forensic death investigations,” Van Zandwijk said. “We already see potential for follow-up studies, such as examining postmortem movement.”