The Detective’s Dilemma

The car stopped next to Sian, and a minute and four seconds later, it drove off—with her in it. But it didn’t make sense: Sian didn’t live that far away. More CCTV footage showed it was a taxi. The driver: Christopher John Halliwell.

Halliwell had a police record and looked like a strong suspect. Fulcher made the decision to place him under covert surveillance, hoping he still had Sian and could lead them to her. Police teams followed him for several days.

Fulcher had to navigate the minefield of an active investigation and intense media interest. The minute police saw Halliwell buy a large quantity of pills (overdose amount), the game was effectively over—he was arrested.

Halliwell said, “Have you got a car? We’ll go.” Instead of taking him to the police station (with access to a lawyer), Fulcher agreed—Sian could still be alive. Fulcher used an exception to the rule for urgent interviews when a life is at stake.

Followed by a large surveillance team, Halliwell led Fulcher to the location where he had taken Sian. He had killed her, he told Fulcher. Fulcher would’ve taken Halliwell in—but then the killer said, “Do you want another one?”

Fulcher couldn’t ignore a potential confession from a self-confessed killer. After Halliwell was taken to the police station, Fulcher was hailed as a hero. But in court, if he had broken procedure, were Halliwell’s confessions admissible?