The National Transportation Safety Administration is expected to reveal if the engineer of the Amtrak train that derailed in Philadelphia was using his cell phone at the time.

Emergency personnel work at the scene of a deadly train wreck in Philadelphia (AP Photo/Patrick Semansky)

Reuters reports that the NTSB has had a hard time determining the status of Brandon Bostian's phone when the train went off the rails on May 12. The issue is mainly due to phone service data that is difficult to track and collaborate with the train's black box, surveillance video and radio transmissions.

Investigators have recently leaned against Bostian being on the phone according to Reuters.

Bostian told investigators he doesn't remember the crash that killed 12 people and says his cell phone was stored tn his baggage. The NTSB has said Bostian, who suffered a head injury in the crash, has been cooperative but says he cannot recall the moments before the accident.

An earlier two-page preliminary report estimates damage from the crash at more than $9.2 million.