White residue found on the gun used to kill supervising Fire Marshal Douglas Mercereau tested out as salt, a forensics scientist told jurors today.But former NYPD criminalist Kristen McDonald didn't know where the salt came from, or how the murdered fire marshal's stainless Smith & Wesson 9mm service weapon wound up with rust inside the slide, behind the muzzle and in front of the trigger guard."The source [of the white residue] cannot be conducively determined," Ms. McDonald testified as to what she wrote in her report that documented her findings.No tests were conducted on the rust found...
