Wednesday, May 25, 2011

GPS evidence: State of Mind of the target suspect




GPS evidence created without the knowledge of the target suspect is one of the most powerful and

convincing forms of evidence available to a proponent of evidence. However, proponents must beware: This statement is predicated on an issue of a state of mind of the actor: created. . . without the knowledge of. .

If the target of GPS related investigation detects tracking, he or she can alter their behavior in ways that will make them look innocent, and use the GPS track evidence as a co-conspirator in a cover up. Unfortunately, if not detected, GPS evidence is so credible, such a cover up is unlikely to be detected. The character of GPS evidence is entirely changed by the target's knowledge that GPS tracking is occurring.

How would someone know that they are being tracked by GPS? They would not see anyone following them, or any evidence of typical surveillance. However, they may realize they are a target of a general


investigation, and attempt to discern if a GPS is attached. They could detect possible tracking by:

  1. Seeing the attachment, but not reacting to the attachment

  2. Finding the attached device (or running over it when it falls off)

  3. Detecting emissions from a GPS transceivers

  4. Discerning levels of surveillance at endpoints of travel, but detecting no surveillance between endpoints.


Typically, GPS receivers, transceivers, or track recorders are connected to a form of transport available excl

usively to the target. Of course, the GPS device is connected in such a way that tampering may be detected (or should be). If time does not permit, because of stealthy on-site attachment, such anti-tamper mechanisms may not be in place.

Again, the attachment phase of a GPS tracker allows the target to "manipulate" GPS evidence collection in several ways if the target knows or suspects he or she is being tracked:

  1. Using the target vehicle in a typical fashion solely be the target until a critical time period-then loaning out the target vehicle to an innocent third party and using alternate transport to commit crime or carry out acts that are the target of investigation-thus using GPS evidence as a false alibi

  2. Again, using the vehicle typically until the critical phase then transferring the GPS device to a innocent vehicle (or removing it temporarily) while the critical acts occur. After the critical acts occur,

    reattaching the GPS device.

  3. Not using the vehicle the GPS is attached to (and using other transport to commit target acts.)

  4. Destroying the GPS receiver-transceiver. This last alternative discloses the targets knowledge of tracking, however, and actually might represent the best-case once the target knows tracking is occurring; at least the proponents know that GPS surveillance has been blown, and can move on to other means of detection.


How can proponents of GPS evidence make sure they are not being played by false GPS evidence from a subject?

  1. Use other forms of verification of the GPS track, (traffic cams, store cams, web cams, etc.) and don't take that track on its face; especially tracks that deviate from a typical vehicle usage. If the GPS says the suspect visited store X, and store X's surveillance footage does not show the suspect where he/she says he/she was, the GPS tracking is not credible.

  2. Treat exculpatory GPS evidence as suspect until confirmed for critical time periods by traditional forms of evidence, such as witness interviews, interviews with the suspect, etc.


Remember: because GPS evidence is technically so credible, even the police or proponents can be "human engineered" into believing the basic presumptions (The GPS was on the vehicle, and the tracked target suspect was driving the vehicle) have been met.

Because GPS evidence is so time specific, even a false track can be used to disclose a deception. How? If an investigator knows where a suspect claims they were during a specific time period, the investigator can use traditional investigative techniques to either confirm or refute an alibi claim. Such techniques should be specific to the person, not just the vehicle tracked.

For instance, a suspect claims to have visited a store, a bank, and gotten gas for his vehicle during a critical time frame. All the suspects claimed locations are substantially physically removed from the crime scene and are verified by a third-party collected GPS track from a GPS transceiver attached to his vehicle giving real time updates. A thorough investigator would not simply accept the GPS track as the last word; rather, the investigator would check time-stamped deposit slips to see if they fell within the GPS record, attempt to get time stamped bank surveillance photos for the time in question, receipts from the gas station, along with photo surveillance, and any other forms of verification to either confirm or refute the presumptions, including witness recollections.

In my fictional example, for instance, its entirely possible that an investigator would find that the suspect had visited the store, the bank and gas station on the day in question, but not during the critical time frame, but two hours before. Although the suspect had receipts within the critical time frame, surveillance showed that an unknowing accomplice, using the suspects vehicle, visited the locations using the suspects vehicle and turned the receipts over to the suspect. The suspect submitted the receipts as if he

The suspect, knowing his vehicle was being GPS tracked, attempted to use the GPS track to close the book on further investigation of his alibi. Witnesses correctly remembered that he was there, but, of course, couldn't place the time frame. The suspect even made a point of going to the witnesses, and asking questions so they would recognize him.

Would it be possible to fool a GPS track to attempt to establish an alibi? Possibly. In the above scenario, imagine that the suspect actually made three stops, all verified for surveillance, but switched to a different vehicle after the third stop, while an accomplice drove the tracked vehicle to unverifiable locations while the crime occurred. Then the suspect and accomplice later met up and swapped vehicles again so the suspect appeared to be driving the tracked vehicle the whole time. Then the suspect intentionally went speeding through a known speed trap and got a ticket, verified on dash cam..


The state of mind of a target of tracking is critical. An unknowing target will create evidence that will either exonerate or implicate the target. A target aware of tracking will be in a position to mislead and derail the investigation. Proponents and opponents of GPS evidence always have to remember that a GPS track is the starting point to an investigation, not the final ending point. Verifying a single stop does not necessarily verify an entire track, and time that is undocumented is undocumented The value of GPS evidence is it limits the scope of the investigation to matters either included in the GPS track, or completely excluded from the track.

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