Screenwriter Pamela Gray describes “Conviction” as a story of “the wheels of justice turning in the wrong direction.”

The second collaboration between Gray and helmer Tony Goldwyn (they made “A Walk on the Moon”) follows the efforts of real-life Betty Ann Waters (Hilary Swank) to clear her imprisoned brother Kenny, framed for a brutal murder in rural Massachusetts.

The true-crime drama extended behind the scenes. “Just before we were going to shoot the scene where Betty Ann gets to open the evidence box,” Gray says, “the prop master told us that he had a helluva a time recreating the murder weapon, because in all the court documentation it was called a ‘kitchen paring knife.’ And, he said, ‘It’s not a kitchen paring knife.'”

Gray and Waters stood frozen. “It was such a shocking moment, the idea that our prop master might have found a piece of the crime that’s still unsolved. Because it changes the possibilities of who might have been the murderer.”

She says the odds of it making a difference now are slim, 30 years after the killing, but “my personal dream would be that this movie can untangle the case, and lead to true justice.”

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