SANTA FE, N.M.—An assistant director unwittingly handed Alec Baldwin a loaded weapon and told him it was safe to use in the moments before the actor fatally shot a cinematographer, court records released Friday show. “Cold gun,” the assistant director announced, according to a search warrant filed in a Santa Fe court. Instead, the gun was loaded with live rounds, and when Baldwin pulled the trigger Thursday on the set of a Western, he killed cinematographer Halyna Hutchins. Director Joel Souza, who was standing behind her, was wounded, the records said. The Santa Fe County Sheriff’s Office obtained the warrant Friday so investigators could document the scene at the ranch outside Santa Fe where the shooting took place. They sought to examine Baldwin’s blood-stained costume for the film “Rust,” as well as the weapon that was fired, other prop guns and ammunition, and any footage that might exist. The gun …