LOS ANGELES — Federal investigators are about to end their silence on what a Metrolink commuter train engineer was texting about before his train collided with a freight last year in Los Angeles, killing 25 people and injuring at least 130 others.

On Tuesday, they plan to release a transcript of the engineer's messages, dozens of other documents and interviews with witnesses conducted during their investigation of the nation's deadliest rail crash in 15 years.

The disclosures on a National Transportation Safety Board Web site will coincide with the start of a two-day NTSB hearing in Washington, D.C., on the Sept. 12 crash in suburban Chatsworth in the San Fernando Valley.

The crash prompted a federal ban on cell phone use by rail workers and led Congress to pass a law requiring "positive train control" technology that can stop a train if it's headed for a collision.

Investigators determined that Metrolink engineer Robert Sanchez sent and received 57 text messages while on duty that day, including one that he sent 22 seconds before his train slammed head-on into the locomotive of a Union Pacific freight train.

The preliminary investigation found that the commuter train failed to stop at a red light just before the crash.

Sanchez was among the dead. His Metrolink train was carrying 220 passengers.