“When I saw that it was dated 1967, I knew we were only going to solve this through forensics, so I went to the archive to look at the exhibits boxes,” says Smith. She found three. “I opened the first and put the lid back on again immediately. Most of our cold cases are in forensically sealed bags with barcodes and case reference numbers. These weren’t. They just had brown cardboard luggage labels saying what they were. It meant they’d never been subject to modern forensic examinations.”