Projects:2017s1-165 Forensic Investigation of Fitness Devices

Project Group Members

Sanjam Kohli

Yuan Li

Project Supervisor

Dr. Matthew Sorell

Introduction

High-tech wearable devices have always been objects of interest in science fiction. From cheap plastic activity bands or rudimentary watches, these gadgets have evolved into elegantly designed devices that can provide greater connectivity, location services, and more importantly, incredible insights into people’s health. These nifty instruments have the capability to monitor a consumer’s heart rate, sleep patterns, and even one’s blood oxygen levels. The smartwatch and fitness band market is dominated by global technology leaders Apple, Samsung, and FitBit. More than 50% of the Australians now own a smartwatch [1]. As these devices are being adopted by a growing number of users, there is an increasing potential for them to become a haven for digital evidence in criminal investigations.

Aim

The project aims to explore the use of wearable fitness devices as forensic evidence, and to establish movement and activities of victims or suspects involved in a homicide investigation. This was achieved by analysing the heart beat and activity records which can be extracted and analysed from the Apple Watch and a FitBit device or their respective paired phones.

Motivation and Significance

A victim’s time of death is crucial to every criminal investigation. Currently, it is extremely challenging to determine the time of death in a homicide investigation using conventional methods. The project attempts to develop a mechanism to establish a more accurate timeline of the incident and a precise time of death using the heart beat and activity logs extracted from fitness devices. The method devised could further assist the South Australian Police (SAPOL), and other law enforcing agencies in future investigations.

Technical Background

Determining the time of death

Estimating the time of death is very crucial to a homicide investigation. It is a critical element of the case timeline. A specific and accurate time of death can corroborate any statements given by suspects in a crime. Despite years of research by forensic experts, no conclusive method has been devised to estimate a victim’s time of death. Presently, the estimation is based on various case specific factors and pathological changes in the human body like changes in body temperature, muscle stiffness, and lividity. In the absence of any witnesses, the complexity of this process increases. By using the current methods, the time of death is usually placed within a range of hours. These processes are highly subjective to errors, and thus it is ‘utterly impossible’ to fix an exact time [2].

Resting and Active Calories

The Basal Metabolic Rate (BMR) is defined as the amount of energy (measured in kilojoules, kJ) burned at rest [3]. BMR is calculated using one’s biometrics like weight, height, age, and sex. Resting calories signify the caloric base burn rate, and are calculated by using the individual’s BMR. Active calories are the calories that are burned due to additional activity.

1 kilocalorie (kCal) = 4.184 kilojoules (kJ)

Total Energy (kJ) = Basal Energy (kJ) + Active Energy (kJ)

Calorie expenditure is relatively linear to heart rate for an average individual, provided that the individual’s heart rate remains within the safe range of 90-150bpm [4].