Amtrak engineer Brandon Bostian talked freely, with an attorney present, with National Transportation and Safety Board investigators Friday. An NTSB spokesman described Bostian as "extremely cooperative."

The derailment of the Washington-to-New York killed eight people and injured more than 200 others. Northeast Regional Train 188 was carrying 238 passengers and five crew members when it derailed shortly before 9:30 p.m. Tuesday.

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Here are five highlights of the investigation into the crash, including new information revealed by the NTSB Friday:

  1. Engineer Brandon Bostian was "extremely cooperative" in the NTSB interview but says he cannot recall what happened. He agreed to be interviewed again.
  2. An assistant conductor in the cafe car of the train said she thought she heard a regional rail train engineer say he'd been "hit by a rock or shot at" and then she thought Bostian said his train had also been hit. Investigators said there was no indication Bostian himself had been hit.
  3. NTSB investigator reported seeing "damage to the left-hand lower portion of the Amtrak windshield."
  4. The FBI has joined the investigation.
  5. Investigators will be working over the weekend to reassemble the train and conduct brake tests.