. >> the sweatshirt was given to forensic analyst mary wong. killer used a .38-caliber handgun, there was the potential of gunshot residue on the sleeves. >> when a weapon is discharged, a cloud of gas is formed and then these particles are then deposited on any surface in the vicinity of the discharge. >> wong processed the sleeves and cuffs with a stub sampler, an aluminum disk with a carbon tape adhesive surface. the sample was bombarded with electrons, and the x-rays revealed three chemical elements -- lead, antimony and barium. >> if those three elements are present, then that leads me to believe that that particle is actually a primal gunshot residue particle. >> this meant kevin rice's killer was wearing this sweatshirt. was it possible that the killer lived in the auburn manor apartments? >> the decision was made by the supervisors to send those keys out with teams of detectives to see, or at least rule out, if those keys went to any of the apartment buildings. >> rockford police. >> investigators tried the keys in dozens of apartment d