Parallels between her treatment and horror fiction included the forcible injection of drugs, helpless captivity on a bed, and burning.
Miss Capper, 16, was held captive tied, blindfolded and gagged at 91 Langworthy Road, Moston, Manchester - the former home of Bernadette McNeilly, one of four people convicted yesterday of Miss Capper's murder.
McNeilly retained keys to the house. Detectives found a small library of occult and horror fiction, including a copy of Misery, a horror novel by Stephen King, the best-selling author.
They also found a cassette which was played constantly to Miss Capper through headphones. It repeated: 'I'm Chucky. Wanna play?' The question is asked menacingly by a possessed doll in the horror film Child's Play.
The prosecution did not claim fictional influences were entirely responsible for motivating the four killers. But the imitation of art, particularly by McNeilly, alarmed police and lawyers involved in the case.
'If you asked me if this case was an argument for censorship, I would say no,' one lawyer said. 'If you asked me whether this material in these minds had some effect on what happened, I would have to say yes.'
In Misery, an injured author is held captive by a deranged woman. She amputates his foot and injects him with drugs.
In Child's Play, a dying felon uses voodoo to transfer his being into a battery-powered doll which can recite three sentences, including: 'Hi. I'm Chucky. Wanna play?' The possessed doll kills three people and survives incineration before being killed through the heart.
There are more differences than similarities between the Capper case and the film and novel. No psychiatric evidence was called during the trial, but Jeffrey Leigh, acquitted of murder but convicted of false imprisonment, described the co-defendants Jean Powell and McNeilly respectively as 'demented' and a 'witch'.
Powell gave evidence that McNeilly assumed the character of Chucky as she filled a hypodermic needle with amphetamine and jabbed it into Miss Capper's arm.
'Bernie (McNeilly) said, 'I'm Chucky. Chucky wants to play'. She was schitzed (drugged) out of her head,' Powell told the court.
An officer on the case, Detective Constable David Osborne, said: 'I don't believe a video can turn someone evil. The capacity is there anyway. But it is possible that exposure to this type of thing sanitises them to horrific acts.'