[Rebel_Ace]

"“...Investigators are in the process of correlating the time stamps in the engineer’s cell phone records with multiple data sources including the locomotive event recorder, the locomotive outward facing video, recorded radio communications, and surveillance video,” the NTSB said Tuesday..."

A few folks here have made light of how long this should actually take, but keep in mind, the time-stamping for all these disparate systems are not synchronized to some national standard, and these investigators pretty much want to pin down the timeline to less than a second in terms of accuracy. Plus, if they are going to use this as evidence to prosecute the engineer, they will have to provide solid backing for how they arrived at the conclusion that he was texting at 00:00:01.96 seconds prior to the impact.

[Paladin2]

I agree that comparing times from different clocks can be nontrivial, but given the necessary lead times here ~15 sec to brake from 100 to 60, they should have a darned good idea of whether this noncisengineer was distracting himself or not.

[9YearLurker]

All this correlation with the event recorder, video, radio, surveillance, etc., is only relevant if his readily available text records show use very close to the time of the crash—and such use of course would be completely against protocol.