Japanese authorities said Thursday they have obtained a data recording device from a container ship to help determine why it collided with a U.S. destroyer, killing seven American sailors.
Japanese transport safety officials said they obtained the voyage data recorder, similar to an airplane's "black box," from the Philippine-flagged ACX Crystal, which is currently docked in Yokohama near Tokyo.
Investigators are examining the ship's movements, including its location, direction, speed and other data to determine the cause of its collision with the USS Fitzgerald early Saturday off Izu Peninsula, west of Tokyo.
"By analyzing the data, we should be able to determine the circumstances of how it crashed," Transport Safety Board spokesman Katsunori Takahashi said.
The safety board is focusing on the cause of the collision and the lessons to be learned, while Japan's coast guard is investigating possible professional negligence in the accident.
U.S. Navy and Coast Guard officials are investigating the destroyer at its home port, Yokosuka naval base.