BEXAR COUNTY, Texas -- The National Transportation Safety Board has been at the scene of Monday's fatal train wreck in Bexar County all week long.

They're waiting on drug and alcohol tests on the train crew to arrive, but said a search of the crew's bags did not reveal any contraband.

Investigators are also waiting to talk to the Union Pacific train engineer who is still in the hospital.

Most of the NTSB investigators are leaving Friday night, but the chief wants to see the tracks at dark firsthand.

"I may do some train rides to see the railroad out there. I need firsthand to see what the engineer saw that night," said Jim Remines, the investigator in charge.

He's already determined there was activity in the train's locomotive Monday morning, but that the brakes weren't applied before the crash.