LAS VEGAS (AP) — Investigators who combed the wreckage of a fatal Las Vegas sightseeing helicopter crash in December say critical steering hardware was disconnected, and the bolt and other tiny parts that should have secured it weren’t found on the scene.

The finding was among documents released Friday by National Transportation Safety Board officials investigating the Dec. 7 twilight crash, which killed a 31-year-old pilot, two honeymooners from India, and a Utica, Kan., couple that was celebrating their 25th wedding anniversary.