For British audiences, it’s a much-loved format. A member of the public chooses who to date from a selection of three suitors, based solely on their answers to questions — the twist being that the candidates are hidden behind a screen so the person on the other side can’t see what they look like. But while Blind Date, hosted by Cilla Black, made gripping viewing for millions in the 1980s and 1990s, as far as anyone knows, it never featured a serial killer.

The same can’t be said for the US forerunner of the show. Rodney Alcala seemed like the perfect ­contestant when he appeared on The Dating Game in 1978, but in reality, the self-styled playboy was in the midst of a murder spree and was a predator so ruthless that one of Los Angeles’s top detectives has called him the “most evil, cunning and remorseless killer” he had ever come across. Tall, handsome and charming, Alcala was “Bachelor Number One”.

He flirted with ­contestant Cheryl Bradshaw — an aspiring actress who had to choose from three suitors — saying suggestively that his “best time is at night”, words that now come with chilling connotations. When the 35-year-old was declared the ­winner, he was introduced to his date as a “successful photographer” who enjoyed ­skydiving and motorcycling in his spare time. What nobody realised, because producers who selected him for the show had failed to undertake background checks, was that he was none of these things.

In reality, he was a convicte.