Investigators are looking into why Sanchez ran through a red signal before the Metrolink train collided with a Union Pacific train Sept. 12 on a curve in the San Fernando Valley community of Chatsworth.
The records obtained from Sanchez's cell phone provider also show that he sent 24 text messages and received 21 over a two-hour period during his morning shift. During his afternoon shift, he received seven messages and sent five.
Sanchez sent his last text message at 4:22:01 p.m. According to the freight train's on-board recorder, the accident occurred at 4:22:23 p.m.
Metrolink board member Richard Katz said in an interview that the NTSB told his agency that another engineer on a Metrolink train has been suspended for sending a text message from his cell phone at about the same time as the Sept. 12 collision. That engineer was not identified.
Katz said Metrolink officials don't know whom the other engineer was texting.
NTSB investigators continue to correlate times from Sanchez's cell phone, the train recorders and data from the railroad signal system, officials said.
"I am pleased with the progress of this major investigation to date," acting NTSB Chairman Mark V. Rosenker said in a statement. "We are continuing to pursue many avenues of inquiry to find what caused this accident and what can be done to prevent such a tragedy in the future."
NTSB spokesman Terry Williams declined to release information about who was exchanging text messages with Sanchez or the content of the messages.
In the days after the crash, several teenage train enthusiasts told a reporter that Sanchez sent them a text message just before the collision. Federal investigators spurred by the media reports interviewed two 14-year-old boys, who they said cooperated in the investigation and provided their cell phone data.
One of the teens showed KCBS-TV a message from Sanchez, which had a 4:22 p.m. time stamp. The message read: "Yea ... usually (at) north Camarillo." The Metrolink 111 train he was operating stops in Camarillo, northwest of Chatsworth.
The collision, which also injured more than 130 people, occurred on a track shared by both freight and commuter trains.
Investigators said Sanchez was supposed to stop and allow the approaching freight train to switch onto a parallel track, but instead went past the red signal and crossed the closed switch, putting the commuter train on a collision course.
The Metrolink train was coming around a curve at 42 mph and the freight train was coming out of a tunnel at 41 mph.
Federal investigators said the engineers of each train had no more than four or five seconds to react before the crash. The freight engineer activated the emergency brake two seconds before impact, but brakes were never applied on the Metrolink train.
Given the speed of the trains and the time each engineer had to see the other, a collision at that point could not have been prevented.
Associated Press writer John Rogers contributed to this report.