The final on-site investigators for the N.T.S.B. left the Tall City on Tuesday.
Those investigators were looking into what went wrong in the moments leading up to the November 15th crash, which killed 4 military veterans and injured 17 other people.
A Union Pacific freight train plowed into a flatbed trailer near the intersection of South Garfield Street and West Front Street.
The trailer was carrying wounded military veterans and their spouses in a parade from downtown Midland to the Midland County Horseshoe Arena -- where the veterans were to be honored in the annual Show of Support Hunt For Heroes banquet.
The N.T.S.B. conducted a sight-distance test at the crash site.
During that test, investigators brought a truck and a train to the scene and re-enacted the fatal crash.
The N.T.S.B. should have a preliminary report out on the crash within 2 weeks.