The engineer driving an Amtrak train was not using his mobile phone in the moments before the train derailed in Philadelphia last month, deepening the mystery of what caused the accident.
Eight people were killed and about 200 more injured in the May 12 derailment.
An updated report by the National Transportation Safety Board says its analysis of phone records "does not indicate that any calls, texts or data usage occurred during the time the engineer was operating the train".
The agency also said the engineer, Brandon Bostian, did not access the train's Wi-Fi system while he was operating the locomotive.
Congress has been pressing the safety board for answers to the key question of whether Mr Bostian was using his phone.
Mr Bostian suffered a head injury in the crash, and his attorney has said his does not remember anything after the train pulled out of Philadelphia's 30th Street Station, the last stop before the derailment.
Engineers are not allowed to use phones while operating trains or preparing them for movement.
Accident investigators have said previously that they have not found any mechanical problems with the train. The track had been inspected not long before the crash.