ORLANDO, Fla. -- Three Walt Disney World employees have been placed on paid leave pending the investigation into Sunday's fatal monorail crash, according to a Disney spokeswoman.

Media relations manager Zoraya Suarez confirmed that a monorail pilot, a monorail shop cast member and a transportation manager were all placed on paid leave. Suarez said the three employees are not being disciplined, but have been placed on leave during the investigation.

The pilot of the pink monorail train, Alan Rubino, was among the trio suspended. His train crashed into the purple train, which was piloted by Austin Wuennenberg, who died in the accident.

Rubino's wife told Local 6 News on Thursday that her husband and Wuennenberg were friends.

"They used to have lunch together," she said.

Mrs. Rubino did not want to discuss the incident in detail. Her husband was not at his Champion's Gate apartment when Local 6 News reporter Jessica D'Onofrio spoke to her.

Meanwhile, after releasing a preliminary report, the National Transportation Safety Board's investigation into the monorail collision is going in a new direction.

A federal investigator with the NTSB returned to Disney on Thursday to dig deeper into what happened in the moments before last weekend's crash.

The investigator first arrived at Disney on Tuesday to look into whether a mechanical malfunction caused the collision that killed Wuennenberg, 21.

The preliminary NTSB report that was released on Wednesday ruled out a mechanical failure, but said for some reason the pink train did not switch onto a spur, keeping it on the same beam where the purple train was located. Wuennenberg also had six passengers on his train.

The report indicated that Wuennenberg had tried to put the purple train in reverse before the collision, meaning it is possible that he saw the pink train backing into him and tried to save himself and his passengers.

After ruling out mechanical failure, the NTSB investigator will now focus on possible human or procedural errors.

The NTSB report said the pilot of the pink train had been instructed to back up, and now the investigator will look into who gave that instruction and why.

"If they found nothing wrong in the mechanical side, nothing wrong with the switching system, then they are likely to zero in on the human factors," former NTSB investigator Peter Goelz said.

Several people are involved in the process of switching a monorail from one beam to another.

A maintenance worker in the monorail storage barn controls the track switch. Once that person flips the switch and verifies that the switch occurred, he or she is supposed to radio monorail control, which is located inside the passenger loading station. A monorail control supervisor then checks his or her own computers before notifying the monorail pilot that it is safe to proceed.

The NTSB will focus on that decision making process for the next step in its investigation.

The investigation is also expected to explore how the trains ended up back inside the train station.

The trains crashed outside the station, but in home video just after the collision, both trains are located in the station.

The on-site investigation is expected to conclude this week, but it will take up to a year for a final report to be published. The report could offer recommendations to Disney on how to make the monorails safer.