May 15, 2017
Case Study: Call Detail Records Analysis in Civil Domestic Litigation
The
conventional wisdom with regard to cellular call detail record analysis is that
it is a tool primarily used by law enforcement to help prove or disprove the
location of a criminal suspect in a given incident. More and more, however, we’re seeing uses for
cellular call detail record (CDR) analysis and mapping in the civil litigation
world, too. We’ll be discussing one such
case in this article.
As a brief
disclaimer, the exact locations of the houses of the parties involved in this
case have been changed for confidentiality, but the rough geographical area and
the cell tower information is the same.
This is a live case which we worked and was recently concluded. So if you still don’t think that CDR analysis
can be of use in your civil case,
keep reading and let us help change your
mind!
Background
In July,
2016, we received a call from a divorced client who was seeking to have his
alimony agreement reviewed by the Court.
He had been divorced from his ex-wife for a number of years, but his
spousal support agreement was costing him thousands of dollars every year, so
he was researching ways to show that his ex-wife was not in compliance with the
agreement. Like many alimony agreements,
his stipulated that if the ex-wife cohabitated with anyone for a period of 12
months or more, the client would be released from the alimony agreement. The client, a very savvy and smart
businessman in his own right, had already hired a traditional private
investigator for surveillance, but the requirements to prove his suspicion in
this case were too great and costly for that to be a viable year-long
solution. However, he surmised that if
he could obtain the cellular call detail records for his ex-wife’s paramour for
a period of 12 months and illustrate that he never stayed at his listed residence and always stayed at the ex-wife’s
residence during the 12-month period, it would constitute cohabitation. The client called us and we assisted with
subpoena language, consultation, cellular record analysis and mapping.
The paramour’s
cellular provider is Verizon Wireless. His
listed address is also the address on the cellular account, which made proving
where he claimed to live a simple matter.
Both houses’ locations were verified through GPS coordinates and were
not that far apart, but as you’ll see, they were far enough apart to make a
difference in this case.
Methodology
Verifying
the data is always a part of best practices.
To that end, we traveled to and physically verified the GPS coordinates
of the houses of interest and the cellular towers primarily involved in this
case. We further verified the type of
cellular device the paramour was using through Verizon Wireless and spent some
time on the phone with technicians from Verizon Wireless to ensure the analysis
in this case was accurate.
Verizon
Wireless records are provided in a series of Excel spreadsheets. The call detail records (CDRs) for the
requested time period are in one spreadsheet and another details every tower in
every switch in every locality that the device connected to for the requested
period. It further details the GPS
coordinates of those towers, the sectors (sides) of the towers and the azimuth
and beam width of the given sectors.
CDRs do not provide cellular signal range, but we can estimate the range
by identifying the next closest tower of the same provider (one of which also
happened to be a relevant tower in this case), measure the total distance and calculate
60% of that distance for the range of each tower in that direction.
Finally,
timing of use was a primary issue.
Because the paramour had a job that required him to travel all over the
local area (in addition to out-of-state locations), the time frame for the
analysis was restricted from 2100 hrs. to 0700 hrs. every day for all 12
months. This would help demonstrate
where the paramour may actually be
laying his head at night. In presenting
our final report, we tallied the percentage of times calls were made from 2100
hrs. to 0700 hrs. on the towers that would likely service both the paramour’s
listed residence and the ex-wife’s residence on a month-by-month basis. The final numbers were greatly skewed toward
the tower and sectors servicing the ex-wife’s house.
Challenges to Analysis
As you can imagine,
this was a large amount of data to analyze, map and report. Additionally, condensing over 12 month’s worth
of cellular call data into a concise, easy to understand report was vital in
this case. To add to the challenges, the
ex-wife’s residence lie on the border of two sectors of the tower that was
closest to it, so if a call were made in the front driveway, it may “ping” off
of sector gamma, but if a call were made from the back of the house, it pay “ping”
off of sector beta (see graphic below).
This proved in the end to be an asset because it increased the percentages
of calls that the paramour was making that hit off of that tower and those
sectors.
Mapping for Analysis
Mapping the locations
of houses, cell towers and sectors in this case was essential. To ensure a concise illustration, the data
was pared down to the two relevant towers, three overall relevant sectors
between them and the two relevant locations – the ex-wife’s house and the
paramour’s listed residence. When the
data is distilled down, here’s what the map looked like:
As we stated
in the final report, there are a number of factors that can affect the range of
cell towers. Terrain, tower load (use at
a particular time), maintenance, weather, etc.
The pie-shaped wedges illustrated here are estimates and should be
considered rough operational ranges.
When all
calls in the specified time frame were added up, 63% of them were sent or received
from tower 468, sectors BETA and/or GAMMA.
While that may not seem like an astronomical amount, when you factor in
that some months 100% of the calls were sent or received from those sectors and
in the same time period, only 1% of calls were sent or received from tower 302,
sector BETA, which would be the tower closest to the paramour’s alleged &
listed residence.
The Outcome
Despite
continued challenges from the opposing party throughout this case and receiving
a subpoena to appear in court to testify as to our findings, the case settled
to our client’s satisfaction about a week before trial. The client’s attorney in the case emailed to
say “I believe that a big reason it
resolved was your report.” Feedback
like that is fantastic to hear. This
case involved many hours of tedious analysis work and we’re very happy it turned
out postively for the client.
The value of
cellular call detail record data in any number of cases should not be overlooked. Recently, I was discussing mobile data with
some personal injury attorneys. The
challenge in distracted driving cases, for instance, is that the device that
may have been in use may be long gone by the time litigation and discovery
comes around. Other evidence, such as
cellular call detail records, can prove very useful and should be considered as
a valuable resource of information in civil cases ranging from alimony to
employment disputes to personal injury.
Author:
Patrick J.
Siewert
Principal
Consultant
Professional
Digital Forensic Consulting, LLC
Virginia
DCJS #11-14869
Based in
Richmond, Virginia
Available wherever you need us!
We Find the Truth for a
Living!
Computer Forensics -- Mobile Forensics -- Specialized
Investigation
About the Author:
Patrick Siewert is the Principal
Consultant of Pro Digital Forensic Consulting, based in Richmond,
Virginia. In 15 years of law
enforcement, he investigated hundreds of high-tech crimes, incorporating
digital forensics into the investigations, and was responsible for
investigating some of the highest jury and plea bargain child exploitation
investigations in Virginia court history. Patrick is a graduate of SCERS, BCERT, the
Reid School of Interview & Interrogation and multiple online investigation
schools (among others). He continues to hone his digital forensic expertise in
the private sector while growing his consulting & investigation business
marketed toward litigators, professional investigators and corporations, while
keeping in touch with the public safety community as a Law Enforcement
Instructor.
