The National Transportation Safety Board said Wednesday that the Amtrak engineer in the deadly train derailment last month near Philadelphia was not using his cellphone before the crash.

The agency has been analyzing cellphone records that would have included any texts, calls or nearby tower transmission activity from engineer Brandon Bostian's cellphone on May 12.

Bostian provided the NTSB with the passcode for his cellphone that allowed investigators easy access to the information.

The crash occurred after investigators said the train reached the speed of 106 mph as it entered a 50-mph stretch north of central Philadelphia, and only managed to slow down slightly before the crash. Eight people were killed in the crash and 200 were injured.

Congress has been pressing the safety board for answers to the key question of whether Bostian was using his phone. Bostian suffered a head injury in the crash, and his attorney has said the engineer doesn't remember anything after the train pulled out of Philadelphia's 30th Street Station, the last stop before the derailment.

Engineers aren't allowed to use phones while operating trains or preparing them for movement, but determining whether Bostian was using the phone was a complicated process.

The phone was used to make calls and send text messages the day of the accident, but inconsistencies in phone records presented difficulties, NTSB Chairman Chris Hart told Congress last week. 

The voice and text messages were recorded in different time zones and may not have been calibrated to the exact time as other equipment on the train, such as a camera focused on the tracks and a recorder that registers how fast the train was moving and actions by the engineer, he said.

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.

Later Wednesday, NTSB officials are expected to testify before the Senate Commerce Committee about train safety. One focus of the hearing is positive train control, a technology that can prevent trains from derailing because of excessive speed.

Congress mandated in 2008 that Amtrak, commuter railroads and freight railroads install positive train control by the end of this year. Amtrak still has to do extensive testing of the system but will meet the deadline, officials have said.

The Associated Press contributed to this report