Smartphone Forensic Alibi

Latest smartphones sport a spectacular array of sensors.  That array expands as you consider all the mobile accessories, like heart rate monitors, that can be used with the phones.

Detailed History

These phones, sensors and apps that operate them can collect and record jaw-dropping detail about the user’s personal history, including the following, coupled with time and date:

* geolocation

* ambient temperature

* body temperature

* barometric pressure

* humidity

* interaction with apps like messaging, social media or motor vehicle functions

* hand motion

* speed and direction of movement

* front and back cameras
Record Keeper

* microphone

* compass

* eye movements!

* REM sleep

* more, more, more

All the data collected by mobile devices is often thought, from a forensics perspective, as providing evidence that the user did something wrong.  Mobile evidence can be used to prove, for example, that a suspect was at the scene of a crime or that a bully transmitted a threatening message to a victim.

Prove Innocence

But mobile sensors are a forensic two-way street.  They might help a user prove a negative . . . prove she did not do something.

In 2011 a motorist persuaded a court to dismiss a speeding ticket in part owing to GPS data from the motorist’s Android phone and tracking app.  The data showed the motorist was traveling within the speed limit, contrary to the opinion of a police officer.

Exculpatory Evidence

When data is marshaled intelligently, a cell phone owner may be able to refute an allegation of drug abuse . . . or disprove an accusation of date rape . . . or dispute a claim of marital infidelity.

This growing panoply of forensic data creates an arms race among adversaries.  They compete to discover

(A) what the data is,

(B) where it is located (on-board, in app-cloud or synced to other device),

(C) how it can be extracted, and

(D) what it means.

Expert Psychological Opinion

Much hinges on interpretation.  Industries of experts and analytical software will blossom to opine on whether the data show the suspect ran from the scene of a crime or merely walked away from an insignificant location.

Forensic psychologists will assess whether a slow, steady decrease in blood pressure denotes a clear conscience . . . or the introduction of a sedative.

–Benjamin Wright

Attorney Wright humbly teaches the law of data security and investigations at the SANS Institute.

Update:  Christa Miller reports that social media proved that a murder suspect was innocent.

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