NEW ORLEANS — A 1991 child rape case was derailed in every imaginable way for 27 years, until what seemed to be a final twist helped prosecutors send a 55-year-old mechanic to prison in 2018.

But now, less than four years into Gerard Ladmirault’s 15-year sentence, the case could be thrown out on a timing technicality, a final U-turn that nobody – not the prosecutors, not the defense attorney, not appellate lawyers, not two different judges and certainly not Ladmirault’s accusers – ever saw coming.