In 1988, Ed Graf was convicted and sentenced to life in prison for killing his stepsons Joby, 9, and Jason, 8, in 1986 by locking them in a shed, dousing it with gasoline, and setting it on fire. Everything was there to prove the case against the Texas man, per an exhaustive analysis in Slate: the motive (a failing marriage he reportedly wanted to save, financial problems that may have been solved with the boys' life insurance policies), loads of circumstantial evidence, and his less-than-stellar reputation (he was said to be a bad husband, father, and employee, accused of embezzlement). There was also the arson science used as evidence against him—"junk science" that's since been debunked and that led to Graf's retrial last year, thanks to a push by Texas fire experts to review old arson cases based on fire-science advances, many of which present a compelling case for Graf's innocence.
What the retrial hinged on: whether jurors would lean toward the strictly scientific strategy of Graf's new defense team or toward the prosecution's circumstantial evidence, motive, and emotional witness testimony. Using the new arson standards, fire experts now said it was more likely the boys were playing with fire and left the shed door open while the fire burned (if the door had been closed, there wouldn't have been enough oxygen to fuel more than a flash fire). Others mention the high carbon monoxide levels in the boys' blood, suggesting it couldn't have been a gas fire intentionally set by Graf, since those fires burn out quickly. The final result, after a deadlocked jury with two holdouts, was shocking: Graf suddenly pleaded guilty—right before the jury decided he was guilty—taking advantage of an obscure legal loophole based on time served that even the prosecutor didn't know about and that set him free on parole eight days after his plea. Read the fascinating story on Slate.