Baldwin shooting: assistant director admits didn't fully check gun

Halyna Hutchins, 42, was declared dead after being airlifted to hospital

The man who handed Alec Baldwin the gun that killed a cinematographer admitted he didn't fully check it, documents revealed Wednesday, as the sheriff investigating the fatal shooting spoke of "complacency" on the US movie set.

An investigation into last Thursday's fatal shooting has recovered 500 rounds of ammunition from the set, Sheriff Adan Mendoza told reporters, adding that detectives believe they were a mix of blanks, dummies and live rounds.