there has been a register of plates since 190a. the database of police dna profiles only began in 1985, and wendy's killer wasn't on it. but part of another plate can tell you where and when a car was registered. and now part of a dna profile can tell you the family the sample likely comes from. you can imagine over 65 million people in the uk, there are around 6.5 million profiles on the dna database. through science, through algorithms, through brilliant individuals, they will narrow that profile down to a population of around 90 people. 90 people who'd given the police their dna and might be related to the tunbridge wells killer. detectives visited and questioned them about their family members. and one family member stood out. and that person was david fuller. we knocked on the door. david fuller answered the door.