What we analyze
- Call detail records (CDRs) from all major carriers
- Historical cell site and sector data
- Timing advance
- Data session records (e.g., Verizon TDR, AT&T, T-Mobile)
- SMS and MMS records
- Tower dump and area dump returns
- Carrier cell site lists and sector azimuths
- Pen register and precision location returns
A tower is not a location
Historical cell site records identify the tower and sector that handled a phone's activity. That places the phone somewhere within that sector's coverage area, which can extend for miles, overlap with neighboring sectors, and shift with terrain, buildings, network load, and the technology in use. A wedge on a map shows directionality, not a pinpoint.
Timing advance records can narrow the estimate considerably, but each carrier records and reports these values differently, and each has its own error ranges. With so many factors at play, correct interpretation matters: it's often the difference between an opinion that survives cross-examination and one that doesn't.
Common problems we find: sector wedges drawn with arbitrary ranges, time zones mishandled between carrier formats (UTC vs. local), "first" and "last" cell confused with the serving cell for the whole session, and conclusions that a phone was "at" an address when the records only support "in the area."
Questions this analysis can answer
- Is the phone's activity consistent, or inconsistent, with being in the area of a particular location at a particular time?
- Does the movement pattern across towers support or contradict a witness's account or an alibi?
- Were two phones in communication, or in the same general area, during the relevant window?
- Was the device actively using voice, text, or data at a specific moment?
- Does the opposing expert's map accurately represent the carrier data, and is the methodology sound?
What you receive
Depending on the engagement: a written review memo, a formal expert report with methodology and opinions stated clearly, accurate maps and demonstratives suitable for court, a rebuttal of opposing analysis, and testimony at hearings, depositions, and trial.
Background in this work
Andrew McDermott has testified as an expert on cellular call detail records in Adams, Denver, and Arapahoe Counties, Colorado, and on cellular data sessions and connectivity in Multnomah County, Oregon. He has taught CDR analysis, timing advance interpretation, and tower dump analysis to investigators and prosecutors nationwide, and completed specialized training in cellular network forensics and cell site expert testimony.